REP builds the PR-4000 and PR-5000 from the same 3×3″ 11-gauge steel, and they look almost identical. So when the J-cups or safeties you want are listed as “5000 Series,” it’s fair to wonder whether they’ll fit a 4000 anyway. Usually they won’t. The PR-4000 has 5/8″ holes and the PR-5000 has 1″ holes, so anything that pins into the upright comes in separate versions. A smaller group fits both, with conditions. This is how PR-4000 vs PR-5000 attachment compatibility works.
The useful question isn’t “4000 or 5000?” but “which series does this attachment list?” Everything below comes from REP’s product pages, rack builders and rack guide, checked September 22, 2026, with hole spacing and package details rechecked October 19, 2026.
Short answer
- PR-4000: pick it if you bench and press inside the rack a lot and want 1″ steps for J-cups and safeties in the bench zone, and the 4000 Series attachments cover what you need. Its entry package also costs less.
- PR-5000: pick it if attachment choice matters most. REP sells several attachments only for its 5000 Series racks, and its Lowered J-Cups 2.0 give 1″ bar-height steps anywhere on the rack.
PR-4000 vs PR-5000: the specs that decide compatibility
REP’s rack guide puts the two racks side by side. The frame steel is the same. The holes, hardware and attachment catalog are not.
| Spec | PR-4000 | PR-5000 | Source |
|---|---|---|---|
| Upright | 3×3″ 11-gauge steel | 3×3″ 11-gauge steel | REP Rack Guide |
| Hole size | 5/8″ | 1″ | REP Rack Guide |
| Hole spacing | 1″ within the bench zone, 2″ elsewhere (front/back); 2″ on the sides | 2″ throughout (no 1″ drilling option); Lowered J-Cups 2.0 paired with Standard J-Cups 2.0 give 1″ bar-height steps | REP Rack Guide; PR-4000 Uprights page; PR-5000 Rack Builder |
| Hole numbering | Laser-cut numbers every five holes | Laser-cut numbers on every hole | PR-4000 and PR-5000 Rack Builders |
| Rackable capacity | 1,000 lb | 1,000 lb | REP Rack Guide |
| Upright heights | 80″ and 93″ | 80″ and 93″ | REP Rack Guide |
| Depth options | 16″, 24″, 30″, 41″ | 16″, 30″, 41″ | REP Rack Guide |
| Attachment options | “Everything except Utility Horn, Barbell Tube Stand, Barbell Hanger, & Pull-Up Bar Connector” | “All attachment options + more to come!” | REP Rack Guide |
| Stainless steel uprights/crossmembers option | No | Yes | REP Rack Guide |
Two rows in that table decide most attachment questions.
Hole size. An attachment that drops a pin or bolt into the upright is sized to the hole. A 1″ pin won’t go into a 5/8″ hole, and a 5/8″ pin sits loose in a 1″ hole, which isn’t what the part was designed for. 5/8″ vs 1″ rack hardware covers why the market split into these two sizes. Adapter sleeves only work one way, a smaller pin in a bigger hole, so they can’t put a 1″ attachment on a PR-4000. The adapter sleeve guide explains when they’re worth using.
Hole spacing. The PR-4000 comes with 1″ spacing through the bench zone. The PR-5000 has 2″ spacing throughout, with no 1″ drilling option. REP’s fix is the Lowered J-Cups 2.0, which sit 1″ below the Standard J-Cups 2.0, so with both pairs you can move the bar in 1″ steps on 2″-spaced uprights. Westside hole spacing explains why bench-zone spacing matters for pressing.
The lowered cups only change J-cup height. They don’t add holes, so safeties, landmines and every other attachment on a PR-5000 still move in 2″ steps. For bench work, that’s the real difference: on a PR-4000 the safeties can sit 1″ closer to your chest at the bottom of the press; on a PR-5000 the J-cups can match that with two pairs of cups, but the safeties can’t. The J-cup guide covers lowered cups and the alternatives.
Because the tube size matches, attachments that clamp around the upright or bolt through REP-specific mounting points have a better chance of crossing over. A matching tube still isn’t a guarantee, as power rack upright sizes explains.
How REP labels attachment compatibility
REP’s product pages follow three patterns. Once you know them, any listing reads quickly.
- Separate “4000 Series” and “5000 Series” versions. The Standard J-Cups 2.0 come as a 4000 Series version, “compatible with the PR-4000 and PR-4100 Folding Squat Rack,” and a 5000 Series version for the PR-5000, Omni, Apollo and Oxylus. The Flip-Down Safeties are also sold per series, in 24″, 30″ and 41″ depths for the 4000 Series and 30″ and 41″ for the 5000 Series. Buy the version that matches your rack.
- One product for both racks. Strap Safeties, the Ares 2.0 cable attachment and the Plate-Loaded Lat Pulldown & Low Row (4000/5000 Series) fit both the PR-4000 and the PR-5000. Even here, read the fine print on height, depth and add-ons.
- 5000 only. Some items name only 1″ hole racks. The Lowered J-Cups 2.0 cover the PR-5000, Omni, Apollo and Oxylus, and are built for “3×3″ uprights with 1″ pin holes.” The rack guide also marks the Utility Horn, Barbell Tube Stand, Barbell Hanger and Pull-Up Bar Connector as unavailable for the PR-4000. One exception: REP says the Utility Horn doesn’t fit the PR-4000 rack itself but does fit REP’s PR-4000 Spotter Arms, which have 1″ holes.
Attachment compatibility examples from REP’s pages
This table only includes attachments where REP’s product page states the fit. It isn’t a full catalog.
| Attachment | PR-4000 | PR-5000 | Source |
|---|---|---|---|
| Standard J-Cups 2.0 | Yes, 4000 Series version | Yes, 5000 Series version | REP Standard J-Cups 2.0 page |
| Lowered J-Cups 2.0 | Not listed | Yes | REP Lowered J-Cups 2.0 page |
| Flip-Down Safeties | Yes, 4000 Series version | Yes, 5000 Series version | REP Flip-Down Safeties page |
| Strap Safeties | Yes | Yes | REP Strap Safeties page |
| Ares 2.0 cable attachment | Yes, listed configurations only | Yes, listed configurations only | REP Ares 2.0 Builder |
| Plate-Loaded Lat Pulldown & Low Row (4000/5000) | Yes, except 24″+24″ 6-post | Yes | REP Lat & Low Row page |
| Rear Base Stabilizer | 4000 version only | 5000 version only | REP Lat & Low Row page |
The lat pulldown is a good example of the fine print
REP’s 4000/5000 Series Plate-Loaded Lat Pulldown & Low Row covers both racks, with three conditions:
- Height has to match. It comes in 80″ and 93″ versions, and an 80″ attachment won’t fit a 93″ rack, or the reverse.
- One PR-4000 configuration is excluded. It isn’t compatible with “the PR-4000 24″+24″ 6-Post configuration as you’d be unable to load weights onto the weight horns.”
- The stabilizer is series-specific. It needs a Rear Base Stabilizer, and “the 4000 Rear Base Stabilizer does not fit the 5000 series power rack. Vice versa, the 5000 Rear Base Stabilizer does not fit the 4000 series power rack.”
So a “4000/5000” attachment can still need a series-specific part. If you’re planning cable work, rack attachments for lats covers what to prioritize.
Ares 2.0 fits both, but only certain builds
REP’s Ares 2.0 builder covers the PR-4000 6-post 16:16, 24:16, 30:16 or 41:16 and the PR-4000 4-post 16″, plus the PR-5000 6-post 16:16, 30:16 or 41:16 and the PR-5000 4-post 16″. The 4-post setups need Mini Front Foot Extensions on the front and back. If your rack depth isn’t on that list, check with REP before ordering.
What to check before you buy
- Your rack’s series. 4000 or 5000, and whether you have 5/8″ or 1″ holes. If you bought used, measure a hole.
- The attachment’s version. If the listing offers “4000 Series” and “5000 Series” options, choose yours. If it names only one series, assume it doesn’t fit the other.
- Height and depth. Cable and lat attachments are sized to 80″ or 93″ uprights and to specific depths.
- Required add-ons. Stabilizers, foot extensions and crossmembers can be series-specific even when the main attachment isn’t.
- Non-REP parts. The Strap Safeties page is plain about it: “Due to machining variables, we cannot guarantee compatibility with non-REP products.” Confirm with the other brand before you mix.
To check a specific attachment, open the Rack Attachment Fit Checker for the PR-4000 or the same checker for the PR-5000, compare both racks spec by spec in the Power Rack Comparison Tool, check the 80″ or 93″ height against your ceiling in the Home Gym Room Planner, and work through the rack attachment compatibility checklist. If you’re also looking at Rogue, the same logic applies in Rogue Monster vs Monster Lite attachments, and the cross-brand pairs are covered in REP PR-4000 vs Rogue Monster Lite and REP PR-5000 vs Rogue Monster 2.0.
PR-4000 or PR-5000: which suits your attachment plans?
REP’s own comparison guide gives the PR-5000 the “largest attachment ecosystem” and aims it at buyers who expect to keep adding on. It places the PR-4000 as compatible with many but not all attachments, with 1″ bench-zone spacing, for lifters who want a solid setup without planning many upgrades.
The spec table backs that up. Pick the PR-5000 if you want the full attachment list, the stainless option, or 1″ hardware shared with REP’s Omni, Apollo and Oxylus racks. Pick the PR-4000 if bench-zone spacing out of the box and a 24″ depth option matter more to you than the last few attachments. Neither is stronger on paper: both are 3×3″ 11-gauge and rated at 1,000 lb rackable. 11-gauge vs 14-gauge steel covers the gauge side.
Whichever you own, buy by series, not by rack name, and read the fine print on anything REP lists for both.
Specifications checked against manufacturer pages on September 22, 2026. Manufacturers change specs; confirm on the product page before ordering.