Li-Ion battery charger suitable for single batteries of type 18650, 16340, 14500, and 17670. It provides a stable output of 4.2 V / 500 mA for safe and efficient charging, with automatic termination when the battery is fully charged. It features an LED status indicator, lightweight design, and power supply via USB or DC adapter. Ideal for flashlights, power banks, and electronic devices that use rechargeable cylindrical batteries.