The Philips HeartStart OnSite AED is the only automatic external defibrillator (AED) on the market available without a Physician’s Prescription. This AED is designed for in-home or office use for high risk patients that should be prepared in the event of a sudden cardiac arrest. The Philips HeartStart OnSite Automatic External Defibrillator (AED) is widely used by laypersons and trained rescuers alike. The portability (weighing 3.3 lbs) allows it to be easily carried to the victim’s side during a sudden cardiac arrest (SCA), and is designed with innovative technology that has produced a defibrillator very easy to set up and use successfully by an ordinary person. The audible clear and natural voice instructions guide the user step by step and keeps pace with the actions being taken. The voice instructions are designed to be sufficiently detailed but not overly wordy to guide even the most novice user. The device is so intuitive that if a voice instruction is not performed, the HeartStart AED recognizes this and asks the user to again to perform the step in a re-worded way, assuming that the first instruction was not understood clearly. In the chaos and crisis of responding to a person who has collapsed due to sudden cardiac arrest, the HeartStart OnSite also provides visual instructions for those users who work better in that mode. These graphic-based visual instructions are designed to communicate instantaneously with minimum reading and interpretation, yet not complete with the voice instructions. This AED delivers its maximum shock strength starting with the first shock.