20pcs Overcharge, Over Discharge, Short Circuit Protection 3.7v 1a 18650 Li-ion Battery Protectiive Circuit Board Lipobattery Protection Board Lithium Polymer Battery Pcb Board 9x3.7mm Charging cut-off voltage:4.2V Discharging cut-off voltage:2.3V Rated current:U1A Charging current: 100 mAI1A Size: 9x3.7mm