Energizer 394BP button cell silver oxide watch battery. Energizer is a worldwide leader in small electronics batteries offering a full line of Watch Electronic Specialty Batteries for applications used in precision engineering tools to power a wide variety of small electronic devices. Everigzer batteries are used in home health devices such as glucose monitors, blood pressure cuffs, and digital ear thermometers. Also, button cells can be used in keyless remote entry systems for cars and homes. Hand held electronic devices also use batteries in calculators, watches, computers. photo camera, audio books, games, toys, and more. 1.55 V.