Cryptic 6.5mm Grendel/7.62x39mm Bolt Carrier Group (BCG) - Complete

Cryptic 6.5mm Grendel/7.62x39mm Bolt Carrier Group - Complete\n\nCoated Bolt Carrier Group BCG for AR-15, M16, or M4 machined from Mil-Spec 8620 aircraft quality steel with shrouded firing pin and Mil-Spec chrome-lined interior. Gas key is chrome-lined and heat treated, secured to the carrier with Grade 8 fasteners and properly staked per Mil-Specs. The bolt assembly is CNC machined from Mil-Spec Carpenter No. 158 steel and shot peened for increased strength per Mil-Spec. HPT (High Pressure Batch Tested) and MPI (Magnetic Particle Inspected).\n\nSpecifications:\n- Manufacturer: Cryptic\n- Fabric/Material: Carpenter 158 Steel, 8620 Aircraft Quality Steel\n- Carrier Material: 8620 Steel\n- Bolt Material: Steel\n- Caliber: 6.5mm Grendel, 7.62x39mm\n- Gun Make: AR Platform\n- Gun Model: M16, M4, AR-15\n- Hand: Ambidextrous\n- Weight: 11.55 oz\n- Included Accessories: Standard features of Cryptic BCG - Complete; Gas Key; Bolt w/ Spring and Ejector; Extractor w/ Spring and viton O-ring; Firing Pin; Cam Pin.\n\nWhat firearm models does the manufacturer say Cryptic 6.5mm Grendel/7.62x39mm Bolt Carrier Group - Complete is compatible with? AR-15, M4, M16.