The RISE Armament Rifle Bolt-Carrier Group ensures the highest level of performance out of your favorite rifle. These Bolt Carrier Groups by RISE Armament reduce friction and increase the smoothness of each shot with high quality steel parts a heat treated carrier and a grade 8 hardened gas key. The RISE Armament AR-15/M-16 BCG is individually MPI tested for quality so you can be confident you're getting overall improved performance. Choose the RISE Armament Advanced Bolt Carrier Group for a great new addition to your rifle.