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. Specifications: Buffer weight: 10oz Buffer length: 4a ^2. No need for a spacer Bumper color: Blue Contents include: 10oz 9mm buffer Carbine buffer spring