Ekrin B37 vs Theragun Prime

Sixteen millimeters versus twelve. If percussion guns have one spec that splits the field, it’s that one, and the Theragun Prime owns it. The Ekrin B37 answers with wins nearly everywhere else: stall force, battery life, noise, attachment count, plus a carrying case in the box. Weight and speed-setting count are dead even at 2.2 lbs and 5 speeds apiece. So the real question isn’t which gun is better on paper. It’s which advantage you’ll actually feel in week three of owning the thing.

Start with the Prime’s case. Amplitude is how far the attachment head travels on each percussion cycle, and a longer stroke pushes deeper into layered tissue on every strike. Most full-size guns, the B37 included, run 12mm. A smaller group reaches 14mm. Only Theragun consistently hits 16mm, thanks to a proprietary motor mechanism, and the extra reach is a genuine differentiator rather than marketing copy. Where it pays off is dense, layered muscle. Glutes, hamstrings, the whole posterior chain. If those big groups are your main target, the longer stroke translates directly into treatment depth a 12mm gun can’t match, and no amount of added pressure fully closes that gap from the shorter-stroke side.

Stall force runs the other way, and by a wider margin. The B37 holds 56 lbs of pressure before its motor stalls; the Prime gives up at 40. For moderate-pressure work, the 10-to-15-minute medium-speed sessions most recreational athletes actually do, the Prime is fine, and its long stroke makes even light sessions productive. Lean in hard and the picture changes. A larger user pressing into glutes or hamstrings will start to compress the Prime’s motor while the B37 keeps its percussion depth steady. The B37 also covers a wider speed band, 1400 to 3200 PPM against the Prime’s 1750 to 2400, and runs quieter at roughly 55 dB versus under 68. That noise ceiling is the difference between background hum and something the whole house hears during a late session. For lighter users, all of this is academic. Press firmly and it isn’t.

Battery is the lopsided one. The Prime’s 120 minutes works out to about 8 sessions at 15 minutes each, so a daily user is charging it weekly at minimum. Forget once and the gun is dead right when the morning routine needs it. The B37’s roughly 8-hour battery runs for weeks on the same schedule, which is a different relationship with the device entirely. You stop thinking about charge state. That matters most for people who keep the gun in a gym bag instead of on a charger, and for anyone who travels with it. A massage gun that arrives at the gym dead is just extra weight, and the Prime invites that failure mode far more often than the B37 does. The B37 sweetens the deal with a fifth attachment and an included carrying case; the Prime ships with four heads and no case. Small things, but they compound in a gym bag.

What the Prime has that no spec row captures is the Therabody app, and it’s not a checkbox feature. Routines are organized by sport (running, cycling, strength, yoga) and by goal, from warm-up to post-workout soreness to pre-sleep wind-down, and Bluetooth lets the app drive the Prime’s speed automatically during a guided session. It also handles the decisions beginners stall on, like which head to use on which muscle and how long to spend per group. If you’re new to percussion therapy, that guidance compresses months of trial and error into a few weeks of prompts. The B37 takes the opposite bet. No app exists for it, and for a certain kind of user that absence is itself the appeal, since there’s nothing to pair or update before a sore hamstring gets treated. Experienced athletes who already know which head goes where will open the Therabody app twice and never again. So the split is fairly clean. Buy the Prime for maximum reach into big, dense muscle groups, or for structured guidance while you build a recovery habit. The B37 is the better daily tool for almost everyone else. More stall force, a far longer battery, quieter operation, and one less thing to remember to plug in.