Standard Numerals...2" ( 50mm ) 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 1-7/8" dia. hole with the rubber friction ring. Dial/Hands/Clock all in one unit. Simply insert into hole. Premium design back time set knob and easy access battery cover. Includes battery.Standard button-cell replacement batteries available at Walmart, Hardware and other stores.(AG13) Overall Diameter: 2 inches. Mounting Diameter: 1-7/8 inches. Mounting Depth: 1/2 inches.