3-1/8" ( 80mm ) Diameter Clock insert unit with brass color plastic bezel. Plastic convex clear lens. Quartz unit, nice quality, attractive and affordable. Holds into a 3" dia. hole with the included metal fastening clips. Dial/Hands/Clock all in one unit. Simply insert into hole. Overall Diameter: 3-1/8 inches. Mounting Diameter: 3 inches. Mounting Depth: 3/4 inches. Requires one AA battery.