Lithium battery. Voltage: 3.0 V.,Diameter: 16.0 mm. Height: 1.2 mm, Hard to find. Is used in many film watches and perpetual calendar watches from Casio, Seiko, Panasonic, Citizen and other manufacturers. CR1612 lithium button cells are also commonly used in car security (car alarm/keyfob batteries), organizer (backup battery for PDA such as Psion etc), glucometer, camera, electric thermometer, calculator, computer equipment (memory backup battery), toys, accutron, communication equipment, electronic watches/clocks, card radios, data pack for video camera.