Features: 4 independent battery slots, charge up to 4 * 18650 rechargeable batteries independently or simultaneously. Dual USB output(1A 2.1A), can charge 2 digital devices at the same time if batteries are inserted. Built-in protective IC, protect your batteries against overcharge, short circuit etc. LCD screen, display the current status of batteries capacity, voltage and current flow while charging. Sliding cover design, convenient for the taking-out and installing of the batteries. Save power, LCD backlight will automatically turn off without operation in 28s.