Features: 3.7V 18650 lithium battery power cord, USB charging cable, approximately 50cm long. Equipped with charging indicator light, it lights up redness when charging and green when fully charging. Build in intelligent charging management chip, capable of high current charging for 18650 high-capacity lithium batteries. When the voltages reaches 4V, the output terminals automatically use pulse current for charging, when the battery voltages reaches 4.20-4.25V, the charger automatically shuts down. It will not cause overcharging of lithium batteries, better extending their service life, safe to use.