Various Access : YDM 4115 A has multiple options to access the lock- Fingerprint, Pin Code, Key Override, Bluetooth and Access Remotely (via Yale Access app) With Yale App and Wifi-bridge you can lock or unlock your door, share keys with family and friends, get notifications when someone comes home and more, all from one mobile app Convenience: It can upgrade your existing door lock and supports door thickness from 40 mm to 80 mm. No wires, no hassle and easy to replace Yale smart door lock warns in case of low battery with alarm and LED. When the batteries are completely discharged, you can easily supply emergency power to the lock with a standard 9V battery Connectivity: Wireless connectivity with Video Door Phones & Home Automation Systems ( Separate Accessories required)