1215KM (1/2 x 28)is Forward Control Design's (FCD) latest offering in the Dead Air sound suppressor mounts line. Threaded for 1/2 x 28, 1215KM is a Keymo compatible brake, compatible with all Dead Air 223 caliber sound suppressors. Nobody likes brakes for 223 ARs, they're loud and obnoxious, and it's FCD's opinion an AR has low enough recoil, a brake is wholly unnecessary. While a brake will reduce felt recoil, it has unjustifiable compromises in increased concussion, noise and flash signature, one also wouldn't want to use a brake from inside a vehicle or indoors, these are trade offs a flash suppressor doesn't have. That said, a brake for a sound suppressor Mfg: Forward Controls Design Llc