The Philips Heartstart On-site AED is a simple, lightweight, and portable device. It features audio prompts to walk the user through the rescue in a clear and concise manner. If a step is missed the On-Site will backtrack and make sure it is completed in a new phrase. Semi-automatic device, which means a button must be pushed for a shock to be administered, and this can be done within 10 seconds of completing CPR. Daily, weekly, and monthly self-tests ensure your device is always ready to complete a rescue. The device itself comes with an 8 year warranty. The battery is good for 4 years after installation in the device. This package comes with a Rigid Waterproof Shell Carry Case. This means this package is perfect for use near water or for when it is going to be shaken around more often.