1.Power supply compatibility：Please note: DC connector dimensions: Outer diameter 3.5 x Inner diameter 1.35mm connectors.The 8.4V dual charging male DC jack connector for 7.4V 2200mAh, 3000mAh, 3500mAh rechargeable lithium polymer batteries. heated mittens、chargers hat、battery heated socks、heat gloves、liner mittens, socks, vests, jackets, hand scarves, and Li-Po by. 2.Power supply specifications：power adapter Input Voltage AC100-240V，50-60Hz，Output Voltage DC 8.4V Output Current 1000mA Output Cable Length 40inch. 3.Working Condition: 7.4v battery charger voltage is 8.4 volts, plug in the charger and connect the battery, red light is on when charging, green light is on when charging is complete. 4.Warm tips: Please charge the battery regularly to prevent damage caused by over-discharge; when charging, avoid placing the charger on flammable items such as sofas, blankets and beds. 5.Warm Service: If you have any comments or suggestions about heated mittens battery heater please feel free to contact us by e-mail, we will give you a satisfactory answer within 24 hours.