Custom Black StealthThe B5 Systems Grip stop will fit any firearm with dead space every 2 3/8" which is used in the majority of rails and handguards on the market today. For hand guards with threaded inserts every 2 3/8", such as the LWRC and Warsport etc. you can bolt the grip stop on directly. This is the Standard size model. For those with hand guards with M-LOK slots, KeyMod, holes, or MOE, use the Universal hardware (included).