Be sure to replace the batteries in your AED so you're prepared for emergency situations. This Defibtech replacement battery pack has a standby life of 5 years when installed in the unit, including daily, weekly, monthly and quarterly self-tests. It provides 125 defibrillation shocks or 8 hours of continuous operating time. Each battery pack comes with a new DAC-410 9-volt lithium battery. Intended for use with the DDU-100 Series.