Arm Assassin Hub

Name: Arm Assassin Hub
Brand: Arm Assassin
Rating: 4.92 (4 reviews)

The Arm Assassin Hub is a small, single-purpose pinch-and-hold grip trainer: a cylindrical hub that bolts to a cable attachment, loading pin, or plate stack, and is gripped bare-handed around its circumference rather than with a conventional handle. It ships in a standard 1 1/4” or shallow 3/4” depth, and in five diameters (1 5/8” through 3 1/2”), so a lifter can dial in difficulty by choosing a narrower or wider hub – narrower is harder to hold on to.

Independent coverage is thin – a handful of GymRadar owner reviews is the only signal – but consistently positive: reviewers across four gyms call it genuinely challenging even at light loads, straightforward for holds and short pulls, and good value against pricier hub trainers from other brands. The recurring gap is that Arm Assassin doesn’t publish which diameter correctly loads standard 45 lb plates, so buyers have had to guess the right size.

Mounting	Bolts to a cable attachment, loading pin, or plate stack
Depth options	Standard (1 1/4") or shallow (3/4")
Diameter options	1 5/8", 2" (1.9"), 2 3/8", 2 7/8", 3 1/2"

How it compares

	Arm Assassin Hub	Micro Gainz Loadable Blob Trainer	Napalm Nightmare 2.0	Grip Genie Grippers
GymRadar rating	4.92/5	4.92/5	4.93/5	4.89/5
Price	$25.00		$100.00	$130.00
Mounting	Bolts to a cable attachment, loading pin, or plate stack
Depth options	Standard (1 1/4") or shallow (3/4")
Diameter options	1 5/8", 2" (1.9"), 2 3/8", 2 7/8", 3 1/2"

4.9/5 · 4 GymRadar reviews

Reviews by source

Expert

4.92/5

4 reviews

A simple, inexpensive pinch-and-hold grip tool: a cylindrical “hub” that bolts to a cable, loading pin, or plate stack and forces the fingers and thumb to grip its bare circumference rather than a handle. Coverage is thin – one small cluster of GymRadar owner reviews is the only independent signal – but it’s consistent: reviewers across four gyms call it genuinely difficult (smaller diameters noticeably harder than larger ones), straightforward to use for holds and short pulls, and a good value against pricier hub trainers from other brands. Functionality is the standout – it isolates pinch/thumb strength that regular lifting doesn’t train. Versatility is the weak spot: it does one thing (a pinch hold), with no adjustability beyond the diameter/depth chosen at purchase, and one reviewer flagged that Arm Assassin doesn’t publish which size correctly loads standard 45 lb plates, forcing a guess.

+Functionality: isolates pinch and thumb strength through holds and short pulls, a movement pattern regular lifting doesn't train (GymRadar: Wberry577)
+Functionality: smaller diameters (e.g. 20mm) are noticeably harder than larger ones (e.g. 30mm), giving a built-in progression by simply choosing a different hub size (GymRadar: Scottsdale Garage Gym)
+Value: cheaper than comparable hub trainers from other brands while still being genuinely challenging (GymRadar: Big Curt)
+Build quality: simple enough design that reviewers report nothing to go wrong with it (GymRadar: Jables)

−Versatility: does one exercise (a pinch hold) with no adjustability beyond the diameter/depth picked at purchase (manufacturer product page)
−Functionality: manufacturer doesn't publish which diameter correctly loads standard 45 lb plates, so buyers have to guess the right size (GymRadar: Jables)
−Durability: no independent long-term-use reports yet -- all GymRadar reviews are from 2026 with no follow-up on wear
−Value: reviewer sample is small (4 GymRadar reviews, all 4.67-5.0) with no independent editorial or video review to corroborate it

$25.00

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