The Angstadt Arms 9mm buffer assembly kit is compatible with both GLOCK(R) and Colt(R) style 9mm AR-15's. Weighing 5.4oz, this buffer is tough enough to withstand the abuse of blowback 9mm firearms and features a dedicated buffer spacer to limit overtravel of your 9mm bolt carrier. Includes 9mm buffer, spacer and carbine buffer spring.