Pepin Adjustable Dumbbells: Specs, Sizes and the REP Collaboration
Pepin adjustable dumbbells explained — the Quebec-made Pro Series and the mass-produced REP x Pepin FAST Series, compared by weight range and dimensions.
Last updated September 2026
Contents11
- Four product lines, sold two ways
- FAST Series: weight range and increments
- Dimensions
- Adjustment mechanism: magnetic pop-pin
- Long-term durability, from two independent reviews
- Fine-tuning below the standard 5 lb step
- How the FAST Series compares to other high-ceiling systems
- Who this fits
- Storage: the cradle question at this weight range
- Why the rail system stays this compact at high weight
- Confirming stock before you plan around either version
Pepin is a real brand — a Quebec-based dumbbell maker (dumbbellpepin.com) that built its name on hand-crafted spin-lock and spring-pin adjustable dumbbells before REP Fitness partnered with them to mass-produce the design as the REP x PÉPIN FAST Series (REP Fitness).
Four product lines, sold two ways
Pepin's own site (dumbbellpepin.com) currently lists four separate lines: the FAST Series, the Olympic Series, the Pro Series and the HD Series, all shipped direct from St-Éphrem de Beauce, Québec (dumbbellpepin.com). The REP x Pepin FAST Series most shoppers searching this brand will find in stock is a mass-produced version of the same design, distributed through REP's own store rather than Pepin's.
Pepin's direct-sold Pro Series includes fixed cast-iron sets and separate adjustable handles rated 5-60 lb or 5-120 lb, sold without plates (dumbbellpepin.com). The site also lists complete Pro Series pairs bundled with weight plates in five total set weights — 110, 150, 190, 230 and 270 lb — for shoppers who want the handle and the plates in one purchase rather than buying separately. Stock on Pepin's direct site fluctuates; at the time of research, every Pro Series listing showed as out of stock, which is worth checking before planning around it.
Pepin also sells its own FAST Series direct, including an adjustable kettlebell version the site explicitly notes does not fit REP's collaboration hardware — a separate compatibility branch worth knowing if you already own the REP x Pepin dumbbells and are shopping accessories. Pepin's direct FAST Series dumbbell pairs are listed by total set weight — 160 lb (2x80 lb), 200 lb (2x100 lb) and 240 lb (2x120 lb) — which lines up with the per-hand ceilings REP sells under its own branding, confirming the two retailers carry the same underlying design at the same weight tiers. The 2.5 lb and 1.25 lb add-on plates and a matching stand are also sold direct as separate line items, same as through REP.
FAST Series: weight range and increments
REP sells the FAST Series as four pairs by ceiling weight — 60, 80, 100 and 120 lb per hand — all starting around 20 lb per hand and moving in 5 lb steps (REP Fitness, Garage Gym Reviews). Optional add-on plates in 1.25 lb and 2.5 lb sizes let you fine-tune below the standard 5 lb step, and offsetting each side independently can also produce effective 5 lb jumps beyond the marked settings (Garage Gym Reviews).
Dimensions
Dumbbell length grows with the ceiling weight you buy: about 11.5 inches for the 60 lb pair, 13.5 inches for the 80 lb pair, 15.5 inches for the 100 lb pair, and 17.5 inches for the 120 lb pair (Garage Gym Reviews). That's compact for the weight — a 120 lb-per-hand adjustable dumbbell under 18 inches long is short compared with most plate-loaded systems at that ceiling.
Adjustment mechanism: magnetic pop-pin
Instead of a twist handle or a rotating dial, the FAST Series uses a spring-loaded pin that rides on a rail beside the handle. Pull the pin out, slide it to the weight marking you want, and it pops back in and holds magnetically (Garage Gym Reviews). The handle itself is 38 mm in diameter — thicker than a standard Olympic barbell — with an electroless nickel finish and volcano knurling. Plates are CNC-cut steel with a black powder coat, and the rail uses UHMW plastic inserts where the pin rides (Garage Gym Reviews). REP Fitness's own product listing confirms the all-steel, CNC-cut plate construction and describes the handle as fully knurled, with laser-engraved weight markings on the rail so the setting is easy to read at a glance.
Long-term durability, from two independent reviews
Two reviewers who used the FAST Series for an extended period both point to the same strengths and the same one real weak spot. Massenomics' long-term review, published after roughly seven months of regular use, reports only minor cosmetic wear and calls out the knurled handles, clean finish and dovetailed plate design as giving the set a premium feel against other adjustable dumbbells on the market. Jungle Gym Reviews' write-up describes an all-steel build with UHMW plastic liners on the plates and cradle bottoms specifically to reduce wear points, and says that build is solid enough to back a lifetime mechanism warranty.
The one recurring complaint in both reviews is the cradle. Massenomics notes that careless reinsertion — sliding a dumbbell back into its cradle at an angle, especially when you're fatigued late in a set — can wedge a plate and stick. REP has responded to feedback on the small pop-pins used for fine 2.5 lb adder weights by announcing lower-profile replacement pins, since the original design could catch on your hand during a fast adjustment. Neither review reports wobble or rattling at rest, though Jungle Gym Reviews notes slightly more plate-to-plate play than the original Canadian-made Pepin design — a byproduct of scaling up manufacturing tolerances for mass production.
Fine-tuning below the standard 5 lb step
REP sells 2.5 lb adder weights that slide onto the rail alongside the main pin, letting you land on a setting between the standard 5 lb marks — useful for warm-up ramps or drop sets where the full 5 lb jump is too coarse (Massenomics review). Offsetting each side of a pair independently, using the same add-on plates, can also produce effective jumps beyond what's printed on the rail, though that takes an extra step compared to a dial system where every increment is built in.
How the FAST Series compares to other high-ceiling systems
Pepin's 120 lb-per-hand pair isn't the only adjustable dumbbell built for lifters past the typical 50-80 lb range. NÜOBELL's S 5100 reaches 100 lb per hand in 5 lb steps inside the same twist-handle body as the 580 (NÜO Athletics) — finer increments than Pepin's 5 lb-with-adders, but 20 lb short of Pepin's ceiling. Ironmaster's Quick-Lock plate-loaded system reaches 120 or 165 lb per hand with add-on kits, in 2.5 lb steps — finer control than Pepin's system, but a manual screw-collar adjustment instead of a one-motion pin.
| REP x Pepin FAST (120 lb pair) | NÜOBELL S 5100 | Ironmaster Quick-Lock (with kits) | |
|---|---|---|---|
| Ceiling per hand | 120–125 lb | 100 lb | 120 or 165 lb |
| Standard increment | 5 lb (10 lb before adders) | 5 lb | 2.5 lb |
| Adjustment motion | Spring-pin on a rail, magnetic hold | Twist handle | Manual locking collar |
| Length at max weight | ~17.5 in | ~21.6 in | ~14.5 in at 75 lb base |
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The pin-and-rail motion is faster than Ironmaster's hand-tightened collars but slower than a single twist or dial turn — you're sliding a pin to a marked position rather than rotating a handle in place. For a lifter who wants the highest ceiling in the smallest dumbbell body and doesn't mind that middle-ground adjustment speed, Pepin's FAST Series is a genuine standout; for the fastest possible switch between sets, a twist-handle or dial system tops out lower but changes weight in one motion.
Who this fits
The FAST Series fits a lifter who wants a compact, high-ceiling adjustable dumbbell and doesn't mind a pin-and-rail motion instead of a single dial turn — the 120 lb-per-hand pair in particular is unusually short for its weight class, and the long-term reviews above suggest the build holds up well past the first few months if you handle the cradle carefully. Pepin's original direct-sold Pro Series adjustable handles and bundled sets are a separate option worth checking against dumbbellpepin.com stock and specs before buying, since availability there has been inconsistent. For a steel-switch alternative built by the same retailer, see our REP Fitness QuickDraw comparison, or our home adjustable dumbbells guide for how the FAST Series stacks up against twist-handle and stackable-block mechanisms more broadly.
Storage: the cradle question at this weight range
A 120 lb-per-hand pair puts real demands on whatever it sits on between sets. REP's FAST Series ships compatible with a matching stand sold separately, built to hold the pins-and-rail dumbbells at their full loaded weight without the cradle itself flexing or tipping under that mass (REP Fitness). If you're buying the higher-ceiling pairs specifically, budget for that stand as part of the purchase rather than assuming any generic dumbbell tray handles 120 lb per hand safely — a tray sized for a 50 lb twist-handle set isn't necessarily rated for more than double that load.
Why the rail system stays this compact at high weight
Most adjustable dumbbells get meaningfully longer as their ceiling weight climbs, because added plates stack along the handle's length. Pepin's rail-and-pin design keeps the 120 lb pair under 18 inches by packing plates more densely around the rail rather than purely extending handle length the way a twist-handle system does — the tradeoff, per the two long-term reviews cited above, is the cradle-alignment sensitivity that both reviewers flagged as the one recurring complaint. A shorter dumbbell body is a real space advantage on a shelf, but it comes with that one practical caveat worth weighing against the footprint savings.
Confirming stock before you plan around either version
Availability genuinely varies between Pepin's own direct-sold lines and the REP collaboration. At the time of research, Pepin's Pro Series showed as out of stock across every listing on dumbbellpepin.com, while the REP x Pepin FAST Series was the version actually available through REP's store. If you're planning a purchase around a specific Pepin product, check current stock on the exact listing you intend to buy rather than assuming both retailers carry every line at all times — the two companies manage inventory independently even though they share the underlying FAST Series design.
No Pepin or REP x Pepin listing here carries a confirmed Amazon ASIN, so there's no direct Amazon link on this page. For a spring-pin or twist-handle set that does, see our best adjustable dumbbells roundup, or the REP QuickDraw comparison for REP's own Lock-N-Load mechanism instead.
General home-gym planning information only, not professional training advice. Specifications and availability change — verify them with the manufacturer or retailer before buying.
Questions people also ask
Is Pepin a real dumbbell brand?
Yes. Pepin is a small dumbbell manufacturer based in Quebec, Canada, known for hand-built spin-lock and spring-pin adjustable dumbbells sold directly at dumbbellpepin.com. REP Fitness later partnered with Pepin to mass-produce the design as the REP x PÉPIN FAST Series, making it more widely available through REP's own store (REP Fitness, dumbbellpepin.com).
How does the Pepin FAST Series adjustment mechanism work?
It uses a spring-loaded pop-pin on a rail beside the handle. You pull the pin out, slide it along the rail to your target weight marking, and it clicks — and locks magnetically — back into place (Garage Gym Reviews). That's a different motion than a twist-handle or dial system; it's closer to a spring-pin barbell collar.
How heavy does the Pepin system go?
The REP x PÉPIN FAST Series is sold in four pairs by ceiling weight: 60, 80, 100 and 120 lb per hand, all starting around 20 lb, with the same core design scaling up to 125 lb per hand in some listings (REP Fitness, Garage Gym Reviews). Pepin's original Pro Series (sold direct) also offers adjustable handles rated 5-60 lb or 5-120 lb, separate from the FAST Series.
How does the FAST Series hold up over months of use?
A long-term review from Massenomics, written after roughly seven months of regular use, reports only minor cosmetic wear and describes the knurled handles, clean finish and dovetailed plate design as giving the set a premium feel next to other adjustable dumbbells. The same review notes one real annoyance: careless reinsertion into the cradle can wedge a plate and stick, especially late in a workout when you're fatigued and less careful setting them down.
Does the Pepin FAST Series come with a warranty or a stand?
The Jungle Gym Reviews write-up describes an all-steel build with UHMW plastic liners on the plates and cradle bottoms to cut down on wear, and says that build quality is what justifies a lifetime warranty on the mechanism — few parts are expected to fail. A matching dumbbell stand and storage cart are sold separately through REP Fitness rather than bundled with the dumbbells.