Complete 10oz AR-15 extra heavy buffer kit gives you everything you need to get your 9mm, 40 S&W or 45acp AR-15 running smoothly. Compatible with both GLOCK® and Colt® style magazines. Contents include: 10oz AR-15 carbine buffer assembly for use with 9mm, 45ACP and 40S&W. The buffer body is extended in length, there is no need for a spacer Carbine buffer spring