Features: Be ONLY suitable for different types of 18650 rechargeable batteries. Capable of charging batteries of different size and with different capacity simultaneously, the battery that runs out of battery will stop discharging and the battery that is fully charged will stop charging immediately. Each of the four battery slots monitors and charges independently. It's powered by USB charger, USB power bank or laptop, so it is convenient when you want to use it. Dual USB output ports can charge your 5V electronic devices (such as phones) when putting the 18650 rechargeable batteries in the slots. Be equipped with reverse connection protection, safe and user-friendly. Adopted superb circuit protection chip, it is equipped with temperature protection, overcharge protection, over-discharge protection, reverse connection protection, output over-current protection, output overvoltage protection. Designed with reactivate function for letting the battery is recharged at 0 volts. Frosted panel, fireproof material, sealed groove body design, compact and fashionable. LCD displays charging current, voltage, working mode. Safe, portable and powerful, it is mini in size and light in weight that is good for your home and travel.