Energizer 357/303 Batteries provide reliable, long lasting power to your important devices. Count on these button cell batteries to power your electronics, whether you need batteries for your key fob or calculator. These Energizer batteries also provide dependable power for your glucose monitor or heart rate monitor. Each 357/303 battery holds power for up to 5 years in storage, letting you keep a ready supply of replacement batteries. Count on Energizer specialty batteries to provide long lasting power when you need it most.