ReVIVE ReStore 4000mAh Portable USB External Backup Battery Charger & Power Bank- Works with Samsung Galaxy S4 , S3 / Nokia Lumia 1020 / HTC One , Droid DNA / Motorola MOTO X , Droid & more! Ultra-slim , 4000mAh battery will charge your USB powered phone , tablet , action camera and other handheld devices on the go! The pack charges your device at a MAX rate of 1A NO MORE OVERCHARGING! Auto-Shutoff function kicks in when the device's battery is full Please Note: On first use , charge it up 100% by USB , then drain fully so that the Lithium-polymer battery chemicals can be exercised and broken in. USB CHARGING TIME: 4.5 hours Compact , travel-friendly design that can slip into your pocket , purse , or pack effortlessly Backed by a manufacturer's 3 Year Warranty / Dimensions - 5 x 2.5 x 0.5 inches ; Weight - 4.51 ounces