The Black Silver USB Rechargeable Door Smart Lock Fingerprint Padlock is a high-tech security solution made of Zinc alloy metal. It allows for quick and easy unlocking through fingerprint identification, providing a high level of security for your home or business. If there is difficulty with fingerprint identification, it may be due to wear and tear, dirt, or water droplets on the fingerprint collection window. To ensure successful identification, it is important to keep fingers and the window clean and dry. If there are finger scratches, it is recommended to register at least three fingerprints for use. A maximum of 10 fingerprints can be registered on the lock. In case of battery failure, simply connect the charging port with a Micro USB to continue using the lock while it charges. After being fully charged, the lock can standby for up to 12 months and will indicate low power by flashing a red light upon unlocking. If no fingerprints are registered, any fingerprint can be used to unlock the lock.