Infant/Child Key Item # 989803139311 The unique Infant/Child Key is used only with the FRx Defibrillator when treating an infant or child who is under 55 lbs or 8 years old. Once the Infant/Child Key is inserted, the FRx automatically reduces the defibrillation energy and provides voice and visual instructions and CPR coaching specifically geared for treatment of infants/children. Graphics on the key show proper pad placement for infants and children