1.Adopt international advanced sensor technology, ensuring the reliable quality. 2. Use 4 AA standard alkaline batteries. 3. Convenient Installation. Directly install for knob locks. 4. Rotating handle avoiding violent damage. 5. Add and delete the fingerprint on the lock directly. 6. Unlock ways: Fingerprint + keypad + Mechanical key. 7. Upper cover reader protection 8. All enroll finger will not lost when battery replacement 9. Low battery power warning function 10. 2 years manufacturer guarantee.