Unlock mode: Fingerprint, Password & key Adel Fingerprint Digital Door Lock 3398 Perfect combination of fingerprint and password, 3 ways to unlock. you can either use fingerprint, password or the mechanical key to open the door; independent mechanical key can be used if the electronic parts fail. Support up to 120 fingerprints memory, and 1 password Reversible handle Moisture-proof design: PCB surface epoxy encapsulated to prevent moisture disseminated in order to maximize the protection of the PCB Self-management: you can add new user, delete, and initialize the lock anytime International standardized operational methods, user no need to re-learn when purchasing another new lock U.S. standard single latch, strengthened internal structure; integrated lock cast structure Anti-pick functions Battery / external power supply: fingerprint lock is supported by four 1.5V AA alkaline batteries which can be used about a million times external power 6V ~ 9V battery can also be used when low voltage normally. Low Voltage alarm: when the battery voltage is low, alarm will sound to notify the user to replace the alkaline batteries timely Operational signal and sounds tips: you can simply figure out the status of the lock by different signal and sound