The black F-ALLDAY Extended Battery Back for GoPro HERO3 from Brunton is a 4000mAh extended battery for the GoPro HERO3 that can extend the run-time by up to four times compared to using the standard battery alone. It features its own back door that seals onto HERO3 Housing allowing the system to be water resistant under IPX5 specification - it is not fully water-tight, however.There is a standard USB type A port on the battery so you can also use it as backup power for smartphones and other mobile devices that draw less that one amp on the go. A 3-in-1 Cable is included which features adapters for Apple 30-pin, Apple Lightning, and micro-USB. The cable is specifically for power and does not carry data. Side access charging door - charges with GoPro or other USB charger