Features: 4-level Indicator LED lamp display power, not working state intelligent automatic shutdown; The built-in lithium-Ion battery protection IC, over-current, overpressure, under-voltage protection; Dual USB output ports. Input requirements: 5V constant voltage power supply can do charge input power, the most matching charger for 5V 1A above Requirements for rechargeable batteries: Compatible Batteries: 18650 batteries, cell phone batteries, flat-panel batteries, MP3 batteries, etc. 3.7v-4.2V polymer Lithium battery. Package Includes: 1 x Dual USB 3.7v to 5V 2A Power Bank Module