Replacement USB charger only compatible with Fitbit Charge 2 wireless Activity. Output: 5V 400-1000mA and full of power consumption of 3 hours. Voltage Regulator (PTC) Inside: Prevent your Fitbit Charge 2 from being damaged by overcurrent when connected to USB power source on PC, Mac, laptop or notebook. Extra replacement charging cable to give your Fitbit Charge 2 a boost in the office, at home or in travels. Make your Fitbit Charge 2 charging become more convenient.