Strong, lightweight aluminum mounts provide a secure, solid platform for Trijicon's RMR(TM) red dot sights. Machined aluminum RM55 positions the RMR at a 45Adeg angle, on the left or right side of a Picatinny rail. Mount behind your primary optic for fast transition from a magnified view to close-in sighting by rotating the rifle slightly. Locking bar and easy-to-grasp grooved thumbscrew ensure fast attachment. Mfg: Trijicon SPECS: Aluminum, hardcoat anodized matte black. Heights measured from top of rail to bottom of sight. Fits Picatinny rails. RM55 - Aluminum, hardcoat anodized matte black. Offset 45Adeg.