CMMG ZEROED Magazine Release Button Black. Installation is simple just screw the adapter button in place then attach the button extension to the adapter done Quality steel construction and serrated extension surface means you get a solid feel and reliable traction every time. Specifications for CMMG ZEROED Magazine Release Button: Manufacturer: CMMG Gun Make: CMMG Color: Black Package Contents: CMMG ZEROED Magazine Release Button CMMG 55AFF9E: ZEROED Magazine Release Button Black