The Philips HeartStart FRx Infant/Child Key turns the FRx defibrillator into a pediatric defibrillator, lowering the shock energy to a level appropriate for children under 8 years old or weighing less than 55 lbs. This unique key is used when immediate care for a child in sudden cardiac arrest is needed, ensuring the FRx is ready for responders of all levels to save lives in schools and community settings.