Lithium ion rechargeable mobile device charger delivers instant power once device is plugged in. Keychain attached for convenience and portability. Charger holds enough power to recharge your mobile phone for 150 minutes of talk time. Holds charge up to 6 months and can be recharged 500+ times by using a USB charger. Four LED battery gauge indicators show charge and discharge status. Push button turns charger on? if inactive for 30 seconds; charger will automatically turn off to save battery power.