Reference

Glossary

Short, plain-English definitions. Each term links to the guides that cover it properly.

A

Affiliate disclosure · also paid link: A clear statement that a site earns from links to stores. Amazon Associates must say 'As an Amazon Associate I earn from qualifying purchases', and the FTC says 'paid link' right next to a link should be an adequate disclosure. Read more: Buying rack attachments on Amazon or AliExpress: what to check first
ASTM F2276 · also Standard Specification for Fitness Equipment: ASTM F2276-23, the Standard Specification for Fitness Equipment. Its abstract covers stability, pinch points, adjustment and locking means, load-transmitting parts, warnings and documentation. It is not a fit standard, and its existence does not mean any product complies. Read more: Rack attachment recalls and pre-use inspection, Rack attachment load ratings: pair, peg, combined, drop and rackable
ASTM F3104: ASTM F3104-21 gives the test methods used with F3105, covering areas such as stability, pinch points, weight disc retention, barbell hook dimensions and load testing. It is a test-method standard, not a specification. Read more: Rack attachment recalls and pre-use inspection, Rack attachment load ratings: pair, peg, combined, drop and rackable
ASTM F3105: ASTM F3105-20 covers externally loaded strength training equipment, benches and external weight storage equipment, and takes precedence over F2276 for those products. A product being in its scope does not mean it was tested to it. Read more: Rack attachment recalls and pre-use inspection, Rack attachment load ratings: pair, peg, combined, drop and rackable

B

Band peg: A short peg mounted low on a rack to anchor resistance bands. Rogue says band pegs should not be used with its RML-390F Flat Foot Monster Lite rack. Read more: Rack pins, band pegs and hardware: hole, pin and bolt sizes
Body only: A listing that sells part of a product without its accessories. Mutant Metals sells an Ultimate Dip Attachment 'body only' variant that does not include handles. Read more: Buying rack attachments on Amazon or AliExpress: what to check first, Will a dip attachment fit my rack?
Bolt-down rack: A rack the maker says should be bolted to the floor. Titan says its non-folding racks bolt down except the X-3 Flat Foot, and gives 3/8 x 3 in lag bolts or concrete sleeve anchors for the bolt-down X-3. Read more: Bolt-down, flat-foot and folding racks: what the maker says before you add attachments
Brand storefront · also brand store: A marketplace store run by the brand or linked from the brand's own site. Synergee's own J-cup page links to Synergee on Amazon in the US and Canada, and Yes4All's page links to Amazon.com product pages. Read more: Buying rack attachments on Amazon or AliExpress: what to check first

C

Caliper · also vernier caliper, digital caliper: A measuring tool with outside jaws for tube size and inside jaws for hole size. It reads more finely than a tape measure, which helps when two size labels are only a millimeter or two apart. Read more: How to measure your rack's uprights, holes and spacing, Hole diameter vs pin diameter: two different numbers
Center-to-center spacing · also pitch, hole pitch, on center: The distance from the center of one hole to the center of the next. Titan says T-2 holes are 2 in on center, although some sections between holes measure 1 in. Read more: Westside vs 2-inch vs metric hole spacing, How to measure your rack's uprights, holes and spacing
Clearance · also gap: The gap between parts that lets an attachment install, pivot or slide. Titan says the gap between its T-3 24 in flip-down safety and the upright is intentional, because the bar could not be installed or flipped down without it. Read more: Hole diameter vs pin diameter: two different numbers, Straps vs pin-pipe vs flip-down safeties vs spotter arms
Clevis pin · also quick-release pin: A pin with a head at one end and a cross hole or clip at the other that keeps it from backing out. REP locks its flip-down safeties with a clevis quick-release pin. Read more: Pins, hitch pins, clevis pins, knobs and magnets: how attachments lock
Combined capacity: A rating for two pieces together. Bells of Steel lists 1,000 lb combined for its Hydra and Manticore Sandwich J-cups without stating the basis, and Synergee rates its J-cup pair at 750 lb combined at equal heights. Read more: Rack attachment load ratings: pair, peg, combined, drop and rackable
Component rating: A rating for one part of a system, such as a strap, not for the whole assembly. Rogue calls its Monster strap 'safety-rated for 10,000 lb'; that is the strap's wording, not a lifting or rackable rating for the system. Read more: Rack attachment load ratings: pair, peg, combined, drop and rackable, Safety straps: rack depth, hangers and the maker's rating
Counterfeit · also fake: A fake copy sold under a brand's name. US Customs and Border Protection says about 87% of counterfeit seizures occur in the small-package environment and advises shopping from authenticated online sources. Read more: Buying rack attachments on Amazon or AliExpress: what to check first
CPSC recall · also recall: A recall announced by the US Consumer Product Safety Commission. Examples on this site: about 1,940 REP PR-4000 and PR-5000 strap safety brackets in February 2021 (21-721), and about 5,500 Rogue barbell brackets in April 2011. Both are historical. Read more: Rack attachment recalls and pre-use inspection
Cross-brand fit · also third-party fit: Using one maker's attachment on another maker's rack. REP says it cannot guarantee compatibility between REP and non-REP items, and that warranties can be voided in those cases. Read more: Rack-brand vs third-party attachments, Attachments for mixed racks: a studio inventory by rack system
Crossmember: A horizontal tube that joins two uprights at the top or base of a rack. Some pull-up bars mount in place of one; REP pairs its 5000 Series Crossmember Multi-Grip Pull-Up Bar with its own connectors and crossmembers. Read more: Rack pull-up bars: crossmember fit, brackets and rating, Rack pull-up and multi-grip bars: crossmember, bracket and rating

D

Detent pin · also ball-lock pin: A pin with a spring-loaded ball that holds it in its hole until pulled out. Rogue's product page for the Monster Safety Spotter Arms 2.0 lists 1 in detent pins, and its manual shows one pin installed per arm. Read more: Pins, hitch pins, clevis pins, knobs and magnets: how attachments lock, Spotter arms for squat stands and racks
Dip attachment · also Y dip, dip station, dip handles: Handles or a frame that mount on the uprights for dips. REP's 4000/5000 Series Dip Station attaches like a J-cup into the rack holes, is anchored by a pin and is rated at 400 lb. Read more: Rack dip attachments: mount type, host list and rating, Rack dip attachments: J-cup style, drop-in and mount-over, Will a dip attachment fit my rack?
Drop-in dip: A dip attachment that drops into the upright holes. REP's Drop-In Dip Attachment mounts with a double C-cup, is listed for the PR-4000, PR-5000, Omni and Apollo, and does not fit the 1000 Series. Read more: Rack dip attachments: J-cup style, drop-in and mount-over, Will a dip attachment fit my rack?
Dynamic drop capacity · also drop rating: A maker's figure for a dropped load rather than a resting one. Titan states an 800 lb combined dynamic drop capacity for its T-3 strap spotter arms, and Rogue states its Monster spotter arms were tested to withstand drops of up to 800 lb; neither gives the test method. Read more: Rack attachment load ratings: pair, peg, combined, drop and rackable, Spotter arms for squat stands and racks

F

Fit attributes · also fit measurements: The measurements that decide whether an attachment fits: upright outside size, hole diameter and hole spacing, plus the attachment's pin size and position, and the rack's inside depth for parts that span the bay. Read more: Identify your rack before buying any attachment, How to measure your rack's uprights, holes and spacing, Rack attachment fit finder
Flat-foot rack · also flat foot: A rack with a wide, flat base made to stand without floor bolts. Rogue says its RML-390F Flat Foot rack need not be bolted down but must not be used with band pegs or Safety Spotter Arms, and Titan says its stabilizer feet do not fit X-3 Flat Foot racks. Read more: Bolt-down, flat-foot and folding racks: what the maker says before you add attachments, Spotter arms for squat stands and racks
Flip-down safety · also spotter bars, flip-down safeties: A steel safety bar that pins into the uprights and flips down into position. REP builds its flip-down safeties from 11-gauge steel with a clevis quick-release pin, rated 700 lb per pair for the 1000 Series and 1,000 lb per pair for the 4000 and 5000 Series. Read more: Straps vs pin-pipe vs flip-down safeties vs spotter arms, Rack attachment load ratings: pair, peg, combined, drop and rackable
Folding rack · also wall-mounted folding rack: A rack whose uprights fold toward the wall when not in use. Titan says its folding racks anchor to wall studs, with stringers recommended, and that not every attachment works on them. Read more: Bolt-down, flat-foot and folding racks: what the maker says before you add attachments, Identify your rack before buying any attachment
Free Return: A return option without return shipping cost. Under AliExpress's 2022 Free Return terms it applied only to items labeled 'Free Return' from participating sellers, with 15 calendar days from receipt to request a return; check the current listing. Read more: Rack attachment warranties and returns by maker, Buying rack attachments on Amazon or AliExpress: what to check first

G

General Certificate of Conformity · also GCC: A certificate the CPSC says a manufacturer or importer must issue for general-use products subject to consumer product safety rules. It does not follow that every rack attachment is subject to a specific rule. Read more: Rack attachment recalls and pre-use inspection, Buying rack attachments on Amazon or AliExpress: what to check first

H

Half rack: A rack with one pair of main uprights and a shorter frame behind them, rather than a full four-post cage. Sunny lists its SF-XF9933 half rack with a 3/4 in hardware peg hole. Read more: Identify your rack before buying any attachment
HDPE (high-density polyethylene): A firm plastic some makers use as padding where the bar rests. Bells of Steel lists HDPE padding in the spec list for its Sandwich J-cups. Read more: Standard vs sandwich vs roller J-cups
Hitch pin · also R-pin, R-clip: A spring-wire pin that clips through a hole to hold a part in place. Titan's T-3 strap spotter arms lock with two hitch pins per arm. Read more: Pins, hitch pins, clevis pins, knobs and magnets: how attachments lock
Hole converter · also converter sleeve: A sleeve fitted over a 5/8 in peg so an attachment can sit in 1 in holes. Synergee includes one with its landmine; for its J-cups it also sells versions without one, so confirm the converter is in the variant you choose. Read more: 5/8 in vs 1 in rack hardware, Hole diameter vs pin diameter: two different numbers
Hole diameter · also hole size: The size of the holes in an upright, which decides the pin class an attachment needs. Makers state it differently: Titan lists 11/16 in holes on the T-3 and gives the T-2 hole as both 26 mm and 1 in. Read more: Hole diameter vs pin diameter: two different numbers, 5/8 in vs 1 in rack hardware, How to measure your rack's uprights, holes and spacing
Hole spacing · also hole pattern: How far apart the holes on an upright are, and how that changes along its height. REP lists PR-4000 spacing as 2 in with 1 in in the bench zone, and Titan lists T-2 holes at 2 in on center without Westside spacing. Read more: Westside vs 2-inch vs metric hole spacing, When an attachment's locking pin does not line up, Rack attachment fit finder
Hole-pattern zone · also bench zone, clean-pull zone: A stretch of an upright where the holes sit closer together, usually around bench and pulling height. Rogue's SML-2 has 1 in spacing through the bench and clean-pull zone and 2 in above and below; Titan lists a similar zone on the T-3. Makers often do not give the zone's start and end heights. Read more: Westside vs 2-inch vs metric hole spacing, When an attachment's locking pin does not line up

I

Impact force: The force when a moving bar is stopped. Physics says that for the same change in momentum, a shorter stopping time means a larger average force, so a resting rating and a drop figure describe different things. Read more: Rack attachment load ratings: pair, peg, combined, drop and rackable
Imperial tubing · also inch tubing: Upright tubing sized in inches, such as 2x2, 2x3 or 3x3 in. One inch is defined as exactly 25.4 mm, which is how every millimeter figure on this site is calculated. Read more: 2x2 vs 50 mm, 3x3 vs 75 mm and 60 mm rack tubing, How to measure your rack's uprights, holes and spacing
Independent report · also reviewer report: A finding from a reviewer or site not tied to the maker, specific to its sample and date. Garage Gym Experiment reported that Titan T-2 lock-in pins could not be used as intended on a REP PR-1100, and Two Rep Cave retracted an earlier report on Titan hole spacing. Read more: Rack-brand vs third-party attachments, When an attachment's locking pin does not line up
Inside depth · also rack depth: The distance between the front and back uprights inside a rack, which straps and pin-pipe safeties must span. Synergee tells buyers to measure it, and sells its straps in 23, 29 and 35 in inside-depth options. Read more: Safety straps: rack depth, hangers and the maker's rating, How to measure your rack's uprights, holes and spacing
ISO 20957 · also ISO 20957-1, ISO 20957-4: A series of safety standards for indoor stationary training equipment. Part 1 (2024) sets general requirements and Part 4 (2016) covers benches and free-standing barbell racks; Part 2 covers machines with stacked weights or other resistance, not rack attachments. Read more: Rack attachment recalls and pre-use inspection

J

J-cup · also J-hook, barbell holder, bar catch: The hook that holds the barbell on the uprights between sets. Each is made for an upright size and pin size; REP's 1000 Series standard J-cups, for example, are made for 2x2 in uprights with 1 in pins. Read more: J-cups and J-hooks: upright size, pin size and the maker's rating, Standard vs sandwich vs roller J-cups, J-cups for 3x3 uprights: 5/8 in and 1 in versions

K

Keyhole · also keyhole pattern: A hole that joins a larger and a smaller opening. Bells of Steel says Manticore holes combine a 1 in and a 5/8 in opening so its 5/8 in Hydra parts can pin in, though they may lift slightly when pushed upward. Titan lists 1 in keyholes on the TITAN Series. Read more: 5/8 in vs 1 in rack hardware, Attachments for mixed racks: a studio inventory by rack system

L

Landed cost: The full cost of an import once duties, taxes and clearance fees are added. The Canada Border Services Agency says courier and broker clearance fees are separate from duties and taxes, and that some low-value courier goods are exempt, with conditions. Read more: Buying rack attachments on Amazon or AliExpress: what to check first
Landing zone · also bar shelf: The part of a J-cup where the bar comes to rest. REP publishes a 0.8 in landing-zone radius, 1.4 in landing width and 5.3 in landing height for its Round Sandwich J-cups. Read more: Standard vs sandwich vs roller J-cups
Landmine · also landmine pivot, landmine attachment: A pivoting sleeve that holds one end of a barbell for angled presses and rows. Synergee's rack landmine locks into the upright with an included pin and is rated to support up to 500 lb. Read more: Rack landmine attachments: mount, sleeve and lock, Rack landmines: upright, safety-bar and sleeve-insert mounts
Landmine sleeve: The tube on a landmine that takes the bar end. Rogue's Monster Landmine 2.0 uses a 2 in, 10 in long sleeve, Synergee says its sleeve takes 1 in and 2 in bar ends, and Titan gives its PPLDM a 2 in sleeve opening. Read more: Rack landmines: upright, safety-bar and sleeve-insert mounts
Locking pin · also safety pin, lock-in pin: A separate pin that keeps an attachment from lifting out of the upright. Oak Club, which sells magnetic pins, tells users to check installation before each lift and to always use a failsafe method of securing the attachment. Read more: Pins, hitch pins, clevis pins, knobs and magnets: how attachments lock, When an attachment's locking pin does not line up, Replacement and magnetic rack pins

M

Magnetic pin · also mag pin, MagPin: A rack pin with a magnetic head that holds it against the upright. Oak Club sells its MagPin 3 in 1 in and 5/8 in shaft sizes and says MagPins are for experienced lifters only, to be checked before each lift. Read more: Replacement and magnetic rack pins, Pins, hitch pins, clevis pins, knobs and magnets: how attachments lock
Maker claim: A statement from the company that makes the product, such as a fit list or a load rating. We report it in the maker's words and say it is the maker's. Read more: Rack-brand vs third-party attachments, Rack attachment load ratings: pair, peg, combined, drop and rackable
Maker load rating · also weight capacity, load rating: The weight figure a maker publishes for its product, in the maker's own words and scope. Read whether it is per pair, per peg, combined, rackable or a drop figure, and never apply it to another part or rack. Read more: Rack attachment load ratings: pair, peg, combined, drop and rackable, Rack safeties: straps, pin-pipe, flip-down and spotter arms
Metric tubing · also 50 mm, 60 mm, 75 mm: Upright tubing sized in millimeters, such as 50, 60 or 75 mm. It is not the same size as the nearby inch label: 2 in calculates to 50.8 mm and 3 in to 76.2 mm, so 50 mm is not 2x2 in and 75 mm is not 3x3 in. Read more: 2x2 vs 50 mm, 3x3 vs 75 mm and 60 mm rack tubing, Upright size finder
Monolift: An attachment with swing-in hooks that hold the bar where the lifter stands, so less walkout is needed. Titan says its T-2 monolift attachments are not compatible with T-2 racks made before October 2020. Read more: Identify your rack before buying any attachment
Mount-over dip: A dip attachment that rests on the rack's safeties instead of pinning into the uprights. REP's 1000 Series dip mounts over two safeties on the same side, with knobs tightened on the top safety and the bottom one supporting the base. Read more: Rack dip attachments: J-cup style, drop-in and mount-over
Multi-grip pull-up bar: A pull-up bar with several grip positions that mounts at the top of a rack. REP lists 1,000 lb and a 1.25 in bar diameter for its 5000 Series Crossmember Multi-Grip Pull-Up Bar without saying what the 1,000 lb covers. Read more: Rack pull-up and multi-grip bars: crossmember, bracket and rating, Rack pull-up bars: crossmember fit, brackets and rating

N

Nominal size · also label size: The size label a maker prints, such as 3x3 in or 2.3 in, rather than a measured size. A 3x3 in label calculates to 76.2 mm, and Bells of Steel labels its 60 mm tubing 2.3 in although 60 mm calculates to about 2.362 in. Read more: 2x2 vs 50 mm, 3x3 vs 75 mm and 60 mm rack tubing, How to measure your rack's uprights, holes and spacing

O

Offset · also pin spacing: The distance between two mounting points on an attachment. Titan states 200 mm between the centers of the two pins on its T-2 spotter arms, so both pins have to line up with holes in the upright. Read more: When an attachment's locking pin does not line up, Westside vs 2-inch vs metric hole spacing
Olympic sleeve · also 2 in sleeve: The 2 in nominal sleeve end of an Olympic barbell, and the plate opening sized for it. Synergee lists a 1.98 in peg diameter for 2 in Olympic plate openings, and REP builds most of its bar storage around standard 2 in Olympic barbells. Read more: Rack plate storage: horn length, sleeve size and per-peg ratings, Bar storage and the rack's working zone
Orientation · also mounting face, datum: Which way an attachment faces and which face of the upright it mounts on: front, back, inside or outside. On a rectangular 2x3 upright the holes run through one pair of faces, so check which face the attachment maker names. Read more: How to measure your rack's uprights, holes and spacing, Rack dip attachments: J-cup style, drop-in and mount-over
Original purchaser: The first buyer of a product, often the only one a warranty covers. Titan's warranty covers the original retail purchaser who bought directly from Titan, and Bells of Steel's covers the original purchaser who bought from Bells of Steel or an authorized retailer. Read more: Rack attachment warranties and returns by maker
Outer dimensions (upright size) · also tube size, upright size: The outside width and depth of an upright tube, such as 2x2, 2x3 or 3x3 in. Attachments that wrap around or sit against the tube are built for one outer size. Read more: How to measure your rack's uprights, holes and spacing, 2x2 vs 50 mm, 3x3 vs 75 mm and 60 mm rack tubing, Upright size finder

P

Per-pair rating: A rating for two pieces used together, not for each one. Synergee rates a pair of its J-cups at 750 lb combined with both cups at equal heights, and REP rates its flip-down safeties per pair. Read more: Rack attachment load ratings: pair, peg, combined, drop and rackable
Per-peg rating · also per-sleeve rating: A storage rating for each peg or sleeve. Synergee rates its plate-storage pegs at 250 lb per peg and 500 lb per pair, and Titan rates its TITAN Series holders at 330 lb per sleeve. Read more: Rack attachment load ratings: pair, peg, combined, drop and rackable, Rack plate storage: horn length, sleeve size and per-peg ratings
Pin diameter · also peg size, pin size: The size of the pin or peg an attachment puts through the upright hole, which can be smaller than the hole. Titan states a 5/8 in pin for its T-3 J-hooks; 5/8 in calculates to 15.875 mm, so it is not the same figure as 16 mm. Read more: Hole diameter vs pin diameter: two different numbers, Replacement and magnetic rack pins, 5/8 in vs 1 in rack hardware
Pin-pipe safety · also pin and pipe, safety pins: A safety made of a long pin that runs through both uprights inside a pipe sleeve. Titan's set uses a pin it labels 5/8 in (16 mm), 34 in long, inside a 23.25 in, 45 mm pipe. Read more: Straps vs pin-pipe vs flip-down safeties vs spotter arms, Rack safeties: straps, pin-pipe, flip-down and spotter arms
Power rack · also power cage, squat cage: A rack with four uprights joined into a cage, so safeties can span the bay between the front and back uprights. Read more: Identify your rack before buying any attachment, Straps vs pin-pipe vs flip-down safeties vs spotter arms
Pre-use inspection · also check before use: Checking an attachment and its pins before each use. Rogue's Monster strap manual says all rigging must be inspected before each use, and Oak Club says to check MagPin installation before each lift. Read more: Rack attachment recalls and pre-use inspection, Pins, hitch pins, clevis pins, knobs and magnets: how attachments lock

R

Rackable capacity · also rackable weight: A maker's figure for the weight an attachment can hold when a bar is set on it. REP lists 700 lb rackable capacity for its 1000 Series standard J-cups and Titan lists 650 lb for its T-3/X-3 pin and pipe set; neither says per piece or per pair. Read more: Rack attachment load ratings: pair, peg, combined, drop and rackable
Revision · also generation, version: A changed version of a rack or attachment sold under the same name. Titan says its T-2 monolift attachments do not fit T-2 racks made before October 2020, so the build date can matter. Read more: Identify your rack before buying any attachment, Buying rack attachments on Amazon or AliExpress: what to check first
Roller J-cup: A J-cup with a roller where the bar rests, so the bar can roll into place. Rogue offers its Ghost Roller J-Cups 2.0 with composite or coated steel rollers and lines the front, back and lip with UHMW. Read more: Standard vs sandwich vs roller J-cups

S

SaferProducts.gov: The CPSC's public database where anyone can search and file product incident reports. The CPSC does not guarantee the accuracy of the reports, and finding no report is not evidence that a product is safe. Read more: Rack attachment recalls and pre-use inspection
Safety strap · also spotter straps, strap safeties: A safety made of nylon webbing hung between brackets to catch a bar at the set height. Rogue lists its Monster Safety Strap 2.0 only for Monster Series units, with a 1 in pin, and Synergee rates its straps to catch up to 750 lb. Read more: Safety straps: rack depth, hangers and the maker's rating, Straps vs pin-pipe vs flip-down safeties vs spotter arms, Rack safeties: straps, pin-pipe, flip-down and spotter arms
Sandwich J-cup · also wraparound J-cup: A J-cup that wraps both the front and back faces of the upright. REP describes its Round Sandwich J-cups as a dual-lock wraparound C-cup design, and Bells of Steel sells its Sandwich J-cups in separate versions by upright and hole size. Read more: Standard vs sandwich vs roller J-cups, J-cups for 3x3 uprights: 5/8 in and 1 in versions
Seller of record · also Sold by, Ships from: The business that actually sells a marketplace item, shown as 'Sold by' on Amazon. Amazon says items shipped by third-party sellers are returned to that seller. Read more: Buying rack attachments on Amazon or AliExpress: what to check first, Rack attachment warranties and returns by maker
Side holes: Holes on the side faces of an upright, used by side-mounted attachments. Titan lists side holes every 6 in on the T-3 and X-3, and says the T-2 has none, which is why some Titan attachments do not fit it. Read more: Identify your rack before buying any attachment, Westside vs 2-inch vs metric hole spacing
Spotter arm · also safety arm: A safety that sticks out from the front of the uprights to catch a bar at the set height. Rogue's Monster Safety Spotter Arms 2.0 extend 24 in from the upright and are listed only for Monster Series units. Read more: Spotter arms for squat stands and racks, Straps vs pin-pipe vs flip-down safeties vs spotter arms, Rack safeties: straps, pin-pipe, flip-down and spotter arms
Squat stand: Two uprights, usually joined at the base, without a cage around the lifter. Rogue's SML-2 Monster Lite squat stand uses 3x3 in 11-gauge uprights; with no inner bay, it takes safeties that stick out from the uprights rather than ones that span a cage. Read more: Spotter arms for squat stands and racks, Identify your rack before buying any attachment
Standard J-cup: A J-cup that hooks onto the front of the upright and pins into one hole, usually lined where the bar rests. REP lists its 1000 Series standard J-cups for the PR-1000, PR-1050 and PR-1100. Read more: Standard vs sandwich vs roller J-cups, J-cups for 2x2 and 2x3 uprights: what the makers list
Static load · also resting load: A load that rests on a part without moving, such as a bar set gently in J-cups. A dropped bar is different: for the same change in momentum, a shorter stopping time means a larger average force. Read more: Rack attachment load ratings: pair, peg, combined, drop and rackable
Steel gauge · also wall thickness, gauge: A number for the wall thickness of steel tubing; a lower gauge number means thicker steel. Rogue lists the SML-2 as 11-gauge, while Titan's own pages list the T-2 as both 14-gauge and 12-gauge. Read more: Identify your rack before buying any attachment, 2x2 vs 50 mm, 3x3 vs 75 mm and 60 mm rack tubing

T

Tolerance: The allowed difference between a stated size and an actual part. No maker in our sources publishes a tolerance for upright, hole or pin sizes, so a converted or rounded figure is never a fit allowance. Read more: 2x2 vs 50 mm, 3x3 vs 75 mm and 60 mm rack tubing, Hole diameter vs pin diameter: two different numbers

U

UHMW (ultra-high-molecular-weight polyethylene) · also UHMW-PE: A slick plastic that makers use to line J-cups, safeties and arms where the bar or the upright would touch steel. Rogue and Synergee name UHMW as a liner material; we found no published wear data for it. Read more: Standard vs sandwich vs roller J-cups
Uniform spacing · also even spacing: Holes at one even distance along the upright, with no tighter bench zone. Titan lists T-2 holes at 2 in on center and does not mark the T-2 as Westside, though its support notes some 1 in sections. Read more: Westside vs 2-inch vs metric hole spacing
Upright · also post, column: One of the vertical steel tubes of a rack or stand. Attachments pin or bolt into the holes along it, so its outside size, hole size and hole spacing decide what fits. Read more: How to measure your rack's uprights, holes and spacing, Identify your rack before buying any attachment, Upright size finder
Usable shaft length: The length of a pin's shaft that can pass through the upright and the attachment. Oak Club lists 4 1/2 in of usable shaft length on its MagPin 3. Read more: Replacement and magnetic rack pins
Usable sleeve length · also loadable length, plate stop: The length of a storage peg that can actually hold plates, up to its stop. Titan lists 11.25 in of loadable length on its TITAN Series holders, and Synergee lists 11.8 in per peg. Read more: Rack plate storage: horn length, sleeve size and per-peg ratings

V

Variant · also version, option: One version of a product sold under one name, such as an upright size or hole size. Synergee sells its J-cups in 2x2, 2x3 and 3x3 versions, with or without a 5/8 in to 1 in converter. Read more: Buying rack attachments on Amazon or AliExpress: what to check first, 5/8 in vs 1 in rack hardware
Vertical bar storage · also barbell holder: Spots that hold barbells upright by one end. REP's 1000 Series Weight Storage has two vertical barbell spots, and REP says most of its bar storage is built around standard 2 in Olympic barbells. Read more: Bar storage and the rack's working zone, Plate and bar storage on a rack: horns, sleeves and ratings

W

Weight horn · also plate holder, plate peg, plate storage: A peg or sleeve on a rack for storing weight plates. Titan rates its TITAN Series plate holders at 330 lb per sleeve, and REP's 1000 Series Weight Storage has eight 8 in horns with up to 2,000 lb for the whole unit. Read more: Plate and bar storage on a rack: horns, sleeves and ratings, Rack plate storage: horn length, sleeve size and per-peg ratings
Westside spacing · also Westside hole spacing, Westside pattern: A hole pattern with tighter spacing through the bench and clean-pull zone. Rogue specifies it on the SML-2 as 1 in spacing there and 2 in above and below; Titan and Force USA also use the name, and other makers' zones may differ. Read more: Westside vs 2-inch vs metric hole spacing