Guide · Weight-stack adders
Add small increments to a weight stack: maker options first
How to add 1.5 to 5 lb to a selectorized stack: the machine maker's own add-on plates first, then a third-party adder, always inside the machine's limits.
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Short answer
Use your machine maker's own add-on or fractional weights first, because they are made for your stack. Use a third-party adder only where the machine maker allows it. Whatever you add, the machine's own load limit still applies: an add-on never raises what the frame, cables and pulleys may carry.
Why small increments are hard on a stack
A selectorized stack moves in fixed steps, often 10 lb or more per plate. Rogue, for example, offers a 300 lb weight stack for its Monster Slinger in 10 lb increments.[1] Moving up one plate can be a large jump on light exercises. Add-on weights fill the gap.
Start with the machine maker's options
| Maker | Add-on | What the maker says |
|---|---|---|
| Force USA (US) | 6 lb pair of 3 lb steel plates | Each splits into 1.5 lb halves; slides onto the stacks of its All-In-One Trainers; retail-only |
| Force USA (UK) | 2 x 1.5 kg pair | Compatibility verified for F100 V2, X15 Pro, G15, G20 V2 Pro and C10 |
| Inspire | 5 lb add-on weights for the FTX | How they attach and the handle increment are not stated |
| REP | Drop-down add-ons on the Altitude Cable Attachment | Shown in the gallery, amounts not stated |
Force USA's US fractional plates come as a 6 lb pair of 3 lb steel plates that each split into 1.5 lb halves and slide onto the top of the stacks of its All-In-One Trainers.[2] The US page says they are sold only at retail locations.
Force USA UK sells a 2 x 1.5 kg pair and lists verified compatibility with the F100 V2, X15 Pro, G15, G20 V2 Pro and C10.[3] The US and UK products are different items; do not convert one into the other.
Inspire lists 5 lb add-on weights as an optional extra for the FTX.[4] The page does not say how they attach.
REP's Altitude Cable Attachment gallery shows drop-down add-on weights, but the page states no amounts.[5]
Third-party adders
Torque Fitness sells a magnetic 2.5 lb Weight Stack Adder Pin in bare steel, 2 inches in diameter and 3 inches long, sold individually.[6] In a product Q&A reply, Torque says its adder pins can hold up to 10 additional pounds.[6] That is a Q&A statement about the adder, not a spec, and it does not increase what your machine may carry.
Add-on plates from other brands are made to sit on a stack, not for a named machine. Check the plate's footprint against your top plate and the spacing of your guide rods before you order, and ask your machine maker whether it allows third-party weights.
The machine's limit comes first
GymPin, which makes stack adders, states that its products do not certify or uprate a machine, that a stronger pin does not raise the machine's rating, and that the machine's permitted load takes priority.[7] Apply the same rule to any add-on: your machine's permitted load is the ceiling. If your manual says nothing about add-on weights, ask the maker before using them.
Stack weight vs handle weight
REP explains that with a 1:1 ratio 20 lb of stack feels like 20 lb, while with a 2:1 ratio it feels like 10 lb.[8] So on a 2:1 machine, do not assume a stack add-on equals the same jump at the handle unless the maker says so. The FTX runs at 2:1, and Inspire does not say whether its 5 lb add-on is stack mass or handle resistance.[4] See 1:1 vs 2:1 cable ratio for why.
Picks that fit2 products
Use these only if your machine maker allows third-party add-on weights. Body-Solid: choose '2.5 lb (WSA2-5)' or '5 lb (WSA5)'; Body-Solid names no compatible machines, so compare the plate's footprint with your top plate.
More on choosing
Power Systems 61999 is a single 5 lb weight; Power Systems says it fits stacks whose guide rods are no more than 3 1/4 in apart, so measure first. On Amazon, check that 'Ships from / Sold by' shows Amazon.com or the brand.
Body-Solid Weight Stack Adapter Plate WSA2‑5 (2.5 lb) / WSA5 (5 lb)
Power Systems Selectorized Machine Add-On Weight, 5 lb (61999)
Next
Questions
How do I add 2.5 lb to a weight stack?
First check whether your machine maker sells add-on or fractional plates for your model. If it does not, a third-party adder such as Torque's magnetic 2.5 lb Weight Stack Adder Pin is one option, but only where your machine maker allows it and within the machine's own limits.[6][7]
Do fractional plates fit any machine?
No. Makers state fit for their own machines: Force USA UK lists verified compatibility with five named models. Stack plates and guide rods differ, so match the add-on to your model.[3]
Is a 5 lb add-on 5 lb at the handle?
Do not assume so on a 2:1 machine unless the maker says it is. Inspire sells 5 lb add-ons for the FTX, which runs at 2:1, but does not say whether 5 lb is stack mass or handle resistance.[4]
Does an add-on weight raise my machine's capacity?
No. GymPin states that a stronger pin does not raise a machine's rating and that the machine's permitted load takes priority. The same logic applies to any add-on.[7]