All 3.7V-4.2V rechargeable lithium batteries, such as cell phone batteries, flat batteries, 18650 batteries, and so on. It could be connected to a lithium battery can also be connected in multiple sections of lithium batteries Lithium positive pole connected B Lithium negative then B- 3 USB output, according to the device automatically recognizes the output 5V1A or 2A current on the phone. Flat charge, you can also charge three mobile phones at the same time. Specifications: 100% brand new and high quality. Apply Battery Type: 18650 battery(not include). Output Voltage: 5V 2.1A Input Voltage: 5V 1A Instructions: Level 4 Capacity indicator Lighting: with LED lights Rated Voltage: 3.7V ( Suit for 3.2V-4.2V. The batteries are in parallel) Material: Electronic components