Shoulder Boulder/Chest Fly Attachment

Shoulder Boulder/Chest Fly Attachment

Build boulder shoulders and poppin’ pecs for that iconic V-taper look! Dumbbell shoulder and chest isolations suffer from inconsistent resistance, but the Shoulder Boulder’s design provides smooth, controlled movement with a superior resistance profile. A standalone rear delt/chest fly station takes up a whopping 5-foot x 5-foot footprint (or more), while this rack attachment mounts to your rack to save space. Easily adjust its height on your power rack for the ideal fit.

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Shoulder Boulder/Chest Fly Attachment Reviews

Based on 5 reviews from Gym Radar users, the Bells of Steel Shoulder Boulder/Chest Fly Attachment have an average rating of 4.33 out of 5. They're currently the #1 most-owned Lateral Raise Attachments on Gym Radar, with 31 home gyms reporting ownership.

5 Reviews

4.33 / 5
Performance
4.20 / 5
Build Quality
4.20 / 5
Value
4.60 / 5

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Medium Sized Craig
The Gravity War Tactical Operations Center
104 reviews
1341 points
(4.33)
4/13/2026
This machine is absolutely at the top of my "in no world do I NEED this, but I like it" list. I could, of course, do lat raises, rear delt raises and front raises with dumbbells (or cables, or resistance bands, or probably a million other ways), but when I used a commercial gym I always enjoyed the dedicated machines, and this brings a little bit of dedicated machine into my home gym setup, and that is good for my soul. Assembly was quick and easy. I have it mounted on a dedicated upright alongside the BOS seal row pad. If I didn't have a dedicated upright for this I would probably never use it because it's heavy and unwieldy and annoying to move. I like that I can just leave it loaded at approximately the correct weight and use it with no delays. I set mine at the correct height for doing chest-supported rear delt rows, and rather than move the machine, I just change my stance to get to the correct height. One note: I mounted it on a Titalt T-3 upright here, which is a 2x3 rack. I 3d printed a couple of shims since this was built for a 3x3 rack.
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Antoine
Antoine's garage gym
4 reviews
226 points
(3.33)
3/19/2026
It's pretty good for lateral raise and chest flies. It's a bit annoying to setup and dismount everytime. If you have a dedicated upright for it it would be ideal. Also the two arms are not symmetrical on my unit wich is a huge PITA.
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Big Canadian Joey
D.I.L.F Dungeon
69 reviews
1077 points
(4.67)
3/18/2026
I went to the show room in Mississauga (Toronto) and got to try this. This thing is super cool, a neat attachment, and offers resistance in a compact space. I very much like this, despite having no need for it.
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Marshall Witmer
Witmer Garage Gym
127 reviews
1539 points
(5.00)
3/7/2026
Another piece I didn't think I needed but now that I have it I dont know how I did some excercises without it. The plate loaded feels good and it can even be attached to the cables for that. I have the 60mm x 60mm and I can use it on my cable tower or my 2x3in power rack which is nice. Only downside is the storing it can be an issue. Hopefully bells of steel comes up with a wall mount or something for it.
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REX PECKINPAUGH
REX PECKINPAUGH's Gym
143 reviews
1664 points
(4.33)
3/4/2026
This is a nice attachment to supplement one’s shoulder routine. It works well and is what I would consider a mid tier offering. It works the shoulders well, but it does not convert well for chest.
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