Made from superior materials, these buffers are ideal for ALL 10/22 semi-auto rimfire applications (22lr, HM2, 22MAG AND HMR), Buffers have an unconditional lifetime guarantee! Easy drop-in bolt buffer stop pin eliminates the metal to metal contact between bolt, receiver pin, the receiver and helps eliminate vibration caused by the metel to metal contact. The recoil buffer also provides a remarkable difference in cycling noise. Simple easy drop in installation. No special tools required.Certified material both in dimension and composition found commonly in the aircraft industry, and are vastly superior to any polyurethane buffer available! In a Magnum application,the buffer needs to be supported in the rear to remove the air gap behind the buffer in a Magnum receiver.