Warm Reminder: 1. 2 AA battery packs are required, not included. 2. When the battery starts working, there will be a "BIBI" voice. The reason is that there is a mini transformer in the battery controller that raises the voltage from 3V to 100V to illuminate the EL line in the mask. This process will produce this sound. All similar products have this problem. Do not worry, it will not affect your use. 3.The battery controller will heat up after a period of use, which is normal and will not affect the use.
