The power bank and the 18650 Li-Ion charger are specifically designed for use with 18650 lithium-ion batteries. This device allows for efficient and safe charging of batteries with a voltage of 3.6 to 3.7 volts. It features two charging slots, enabling two batteries to be charged simultaneously, making it particularly convenient to use. The power bank is ideal for various applications where a reliable power source is needed, whether for portable devices or other electronic applications. The use of lithium-ion technology ensures high energy density and a long battery life. The charger is user-friendly and allows for easy handling. Please note that the batteries are not included and must be purchased separately. This product is an excellent choice for anyone looking for a reliable and efficient power supply solution.