Mounts Onto 3 1/4" or 4" (83MM or 102MM) Conduit Boxex, or Other Recessed Outlets. Cover Accepts Devices With Mounting Screw Centers Of 2 3/4", 3 1/2", or 4 1/16" (70MM, 89MM, or 103MM). Can Be Used With 5736 Blank Cover As A Pull or Junction Box. Outside Diameter 6 3/8" (162MM).