This M5070A Battery is the replacement lithium battery for the Philips Heartstart HS1 and FRx defibrillators.  This a genuine Philips battery, not a generic equivalent.  It will last for up to four years in standby mode, and provide up to 300 shocks when used.  Hearstart batteries are not rechargeable and should be replaced when they reach their expiry date.  These batteries will not run down if they not inserted into a defibrillator, but they must be used within 5 years of the date of manufacture.