Kastar 2 pack high capacity batteries. Use high quality Japanese cells for longer battery life with no memory effect. New smart slim USB charge design, easy to carry. Input: 5V 2A; Output: 4.2V/8.4V 600mA. Can be powered by USB Wall & Auto Charger or a Computer, LED indicate: Red light for charging; Green light for standby or full-charge. With the newest generation of CPU control, automatic constant current control prevents battery from overcharging and short circuit. Patented charger with FCC, CE and ROHS certification. All items include 18-Month manufacturer warranty.