The Defibtech Lifeline Semi-Automatic AED is a simple but powerful device. It is durable and simple in design. Lightweight with a large handle for easy transportation Easy to use for both trained professionals and first-time users. Loud and clear audio prompts help to walk the user through a rescue. Progress lights on the device to give clear visual guidance. The device will signal the user when to press the shock button if a shock is required. Includes a 9V battery that powers the devices daily, weekly, monthly, and quarterly self-tests. Must be replaced yearly. Comes with a standard battery with a life of 5 years after installation in the device.