LBE Unlimited Standard Carbine Length Recoil Buffer, Fits AR-15 ARBUFF The AR-15 Standard Carbine Recoil Buffer is the most widely used buffer in the AR-15 recoil buffer family. It can be utilized across many different styles of carbine builds featuring different barrel lengths and gas port sizes. Features 3x internal steel weights. For use with a Carine Buffer Tube only. LBE Unlimited is a leading producer of US Made gun parts and accessories.