... panel and open it with mechanical key.c. Use outside battery box to open the locker when the battery power is low ... Union,PaypalApplication:Swimming pool , sauna bathing spot,golf course,gymnasium locker,enterprise,school,hotel, supermarket storage cabient,etc Packing and DeliveryBox ... lock body optional)Different TM keychain optional:Usage: Waterproof RFID locker Lock TM card automatic easy to open