Duracell CR123A 3V Lithium Battery,12 CT

I recently upgraded my home alarm system to wireless and all of the ADT contacts use this size battery. I looked at cheaper alternatives, but there were many complaints about other brands that the batteries just didn't last long enough and required replacement. I decided to go with Duracell Lithium because it is a tested, tried and true brand of batter. Yes, it is more expensive than other brands, but you are paying for quality, less risk of leakage, and good value for the money. You may spend more up-front, but you will be replacing batteries less often.