Guide · Rack pins, band pegs and small hardware
Hole diameter vs pin diameter: two different numbers
Rack makers print the hole, the pin or both, and they are not the same number. How to read each, with examples from Titan, REP, Bells of Steel and Sunny.
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Picks that fit
- Titan Fitness T‑3 Series J-Hooks, pair (SKU 401348)Check price on Amazon
- Bells of Steel magnetic rack attachment pin, Hydra (3x3, 5/8 in holes), 5.0 in shaft, single (MAG-PIN-HDR)Check price on Amazon
- Bells of Steel magnetic rack attachment pin, Manticore (3x3, 1 in holes), 5.1 in shaft, single (PIN-MAG-MTC)Check price on Amazon
Short answer
The hole in your upright and the pin on your attachment are two different numbers. Titan, for example, lists 11/16 in holes on the T-3 and a 5/8 in pin for its T-3 J-hooks. Read which one a maker is printing, record both, and choose attachments by the pin size and host list the attachment maker states, never by the hole alone.
Picks that fitAll picks and how to choose
- Titan Fitness T‑3 Series J-Hooks, pair (SKU 401348)Check price on Amazon
- Bells of Steel magnetic rack attachment pin, Hydra (3x3, 5/8 in holes), 5.0 in shaft, single (MAG-PIN-HDR)Check price on Amazon
- Bells of Steel magnetic rack attachment pin, Manticore (3x3, 1 in holes), 5.1 in shaft, single (PIN-MAG-MTC)Check price on Amazon
Makers print the hole, the pin or both
A listing that says "5/8 in" might mean the hole, the pin or the bolt class. Look for the word next to it:
- Hole diameter: the opening in the upright.
- Pin diameter: the shaft on the attachment that passes through the hole.
- Hardware: often the bolt and pin class of a whole rack line, not a measured hole.
On one system the hole is usually a little larger than the pin, so the pin can pass through. How much larger is the maker's design choice, and no maker we found publishes a fit tolerance.
The Titan T-3 example
Titan lists the T-3 Series with 2 x 3 in uprights and 11/16 in holes.[1] Titan's support page states a 5/8 in pin size for its T-3 J-hooks (JHOOK_T3, SKU 401348).[2] The same support page gives an 11/16 in hole size for the mounting bracket of its SPHPUBAR_T3X3TS pull-up bar.[2] The X-3 also lists 11/16 in holes.[3]
So a T-3 owner who reads "11/16 in" and shops for 11/16 in pins is reading the wrong number. The maker's J-hook pin is 5/8 in.
What the conversions say
All of these are calculated from the exact inch (25.4 mm):[4]
| Size | Calculated |
|---|---|
| 5/8 in | 15.875 mm, slightly less than 16 mm |
| 11/16 in | 17.4625 mm, about 1.59 mm (1/16 in) larger than 5/8 in |
| 3/4 in | 19.05 mm |
| 1 in | 25.4 mm |
5/8 in and 16 mm are not the same number, even when a maker prints them side by side.[4] The 1/16 in between an 11/16 in hole and a 5/8 in pin does not, by itself, tell you an attachment fits or locks.
When the maker gives two hole sizes
Titan gives the T-2 hole size as 26 mm in its spec table and as 1 in holes in its description.[5] 26 mm is about 1.024 in, so "1 in" is a rounded label. Record both.
REP's ISO arm FAQ, an undated maker PDF, says the PR-4000 version of the arms fits an 18 mm hole and the PR-5000 V2 version fits a 27 mm hole.[6] REP's rack guide lists those racks by hardware class (5/8 in and 1 in), not by hole size.[7] The FAQ figures are generation-specific; ask REP which applies to your rack.
Keyholes
Bells of Steel says Hydra racks use 5/8 in holes and Manticore racks use 1 in holes.[8] It also says Manticore side holes combine a 1 in opening with a 5/8 in opening so 5/8 in Hydra attachments can pin in.[8] That keyhole statement covers Bells of Steel parts on Bells of Steel racks only.
By system
| System | Hole the maker lists | Pin or hardware the maker lists |
|---|---|---|
| Titan T-3 | 11/16 in[1] | 5/8 in J-hook pin[2] |
| Titan X-3 | 11/16 in[3] | not stated on that page |
| Titan T-2 | 26 mm and "1 in"[5] | not stated |
| Bells of Steel Hydra | 5/8 in[8] | Hydra parts |
| Bells of Steel Manticore | 1 in, with 5/8 in keyhole side holes[8] | Manticore parts |
| Sunny SF-XF9933 | 3/4 in hardware peg hole[9] | not stated |
Sunny lists a 3/4 in hardware peg hole on its SF-XF9933 half rack.[9] That is 19.05 mm, so it is not a 5/8 in system.
Can a smaller pin go in a bigger hole?
Follow the attachment maker's stated host list and pin size. Never swap in a thinner pin, add a homemade sleeve or shim, or drill or ream a hole. If the maker does not list your rack or hole size, ask before you buy.
Pins and hooks that state their size
Picks that fit3 products
Titan T-3 J-Hooks: Titan T-3 racks only. Bells of Steel magnetic pins: the Hydra pin (MAG-PIN-HDR) for Hydra racks with 5/8 in holes, the Manticore pin (PIN-MAG-MTC) for Manticore racks with 1 in holes; Bells of Steel states no load rating for either pin.
More on choosing
On Amazon, check that Ships from / Sold by is Amazon.com or the brand.
Choose the Titan T-3 J-Hooks for a Titan T-3 rack
Magnetic pin for Hydra racks (5/8 in holes)
Magnetic pin for Manticore racks (1 in holes)
Next
Questions
Is a 5/8 in rack the same as a 16 mm rack?
No. 5/8 in works out to 15.875 mm, slightly less than 16 mm. Some makers print 16 mm beside 5/8 in as a rounded label; treat them as different numbers.[4]
My rack says 11/16 in holes. Which pin size do I need?
Use the pin size the attachment maker states for your rack. Titan lists 11/16 in holes on the T-3 and a 5/8 in pin for its T-3 J-hooks, so the hole and the pin are different numbers on the same system.[1][2]
Can a smaller pin go in a bigger hole?
Only if the attachment maker lists your rack or hole size as a host. Never improvise with a smaller pin, a sleeve or a shim of your own.
What does Titan's T-2 hole measure?
Titan gives it as 26 mm in its spec table and as 1 in holes in its description. Record both and ask Titan which applies to your rack.[5]