Using this 18650 battery charger case is easy. First, open the spring - clip design part of the case. Then, gently place your 2 x 3.7V 18650 batteries into the holder. Make sure the batteries are properly seated. When it comes to maintenance, keep it in a dry place to prevent the metal parts from rusting. Avoid dropping it as it may damage the internal structure. If you're not using it for a long time, remove the batteries to maintain their lifespan. And always be careful with the wires, don't pull them too hard as it might break the connection.