2-1/2" ( 65mm ) Diameter Clock Insert Fit-up Unit with brass color plastic bezel. Plastic clear lens. Quartz unit, very nice quality, attractive and affordable. Holds into a 2-3/8" dia. hole. Dial/Hands/Clock all in one unit. Simply insert into hole. Premium design back time set knob and easy access battery cover. Requires one AAA battery, not included. Overall Diameter: 2-1/2" inches. Mounting Diameter: 2-3/8 inches. Mounting Depth: 9/16 inches.