A roll of ten 123 lithium batteries to fit the ZOLL® AED Plus® automated external defibrillator. The ZOLL AED Plus uses ten batteries in two banks of five with a fail-over system - if one bank fails, the other takes over. Battery life is approximately five years with the defibrillator in standby mode, shorter if the defibrillator is used. The ZOLL AED Plus emits a warning signal when the batteries need to be replaced. When changing batteries, always replace all ten batteries at once.