The double USB charger is used to charge the Li-on battery, it works for action cameras.Rechargeable battery capacity: 1050 mAhRechargeable battery voltage: 3.7 V.Charging voltage: DC 4.2V, 1 A max.Charger:Input: 5 V / 2 A.Output: 4.2 V / 0.75 A (X2).Dimensions: 2.0 x 1.6 x 0.6 in.Weight: 0.56 oz.In the box:1 dual USB battery charger.1 USB cable