Dual Function: 1) Charge lithium cells from a 5V power source 2) Protect battery from over-discharge and over-current Charge input: 5V DC Maximum charge current: 1000mA Charge cut-off: 4.2V Discharge protection cut-off: 2.5V Over-current protection cut-off: 3A USB-C input Size: 2.6x1.7cm