This replacement battery pack for Lifeline AED DDU100 defibrillators has a standby life (installed in the unit) of five years (including daily, weekly, monthly and quarterly self-tests), 125 defibrillator shocks, or eight hours of continuous operating time. Each battery pack comes with a new DAC-410 9V lithium battery. Battery Type: Specialty; Battery Size: 9V; For Use With: Lifeline AED Defibrillators.