Energizer, 1.5V, watch/electronic silver oxide battery, comparable to Duracell #D377b. Silver Oxide Batteries are designed for continuous low-drain and high pulse on demand so they are perfect for watches, toys, glucose monitors, calculators and more. At 1.55 volts, the silver oxide/zinc alkaline battery offers higher voltage than comparable mercury batteries and a flatter discharge curve than alkaline manganese dioxide batteries. Mercury-free battery also has good resistance to shock, vibration and acceleration. Cell size is 377. It is a replacement for 376/377, 377BP, D377, SB-AW, SR626SW and SR66.