Energizer EL123APB-2 3-Volt Lithium Photo Battery (2-Pack)
The Energizer 3-volt lithium photoelectronic battery was designed for  use in photographic devices, calculators, memory backup, pocket pagers, watches,  and other demanding equipment. This lithium battery delivers endurance and  reliability in high and low temperature operations and has a storage life of up to  10 years when stored at room temperature.