MaxPowerCell CR123a

CR123 batteries were originally designed to fit into numerous cameras. And so, in spite of its relatively recent introduction to the world of batteries, this squat battery, is relatively common. Many of Honeywell's products, for example, use the battery since it provides consistent power, and is a bit more compact than its more widely used AA counterpart.

Despite being small, the battery will last about five to six years in a product that has general usage. Its usage in door contacts, such as the Honeywell 5816, can vary the life of the battery vary greatly. When put in a door contact attached to a heavily used door, the battery is likely to last for a much shorter period of time.