I purchased and attached a GA SPR OTB brake for my franken-gun. I have a 14.5" medium weight mid-length BCM barrel with a 13" UTG Pro Super Slim rail. The brake was shipped quickly, in less than three days, and I promptly affixed it to my AR which had previously held an A2 style "birdcage" comp. The fit and finish is excellent and the quality is apparent right out of the package. The brake came with a shim set and some sweet GA stickers.
Installation was incredibly simple and took me all of five minutes. I bought this brake to minimize recoil and to eventually purchase and accept a GA OTB can. The brake functioned flawlessly and indeed reduced perceived recoil by a considerable amount. I am very happy with this product and anticipate purchasing many more Griffin products.
I am a Marine/DoD/LE vet and have been using an AR of one type or another in a professional capacity for over a decade. I am impressed by this product and by this company overall.