Smart Lock System Doesn't Get Better. Gain Access Using Smart Phone, Bluetooth Fingerprint, Password, Key, Card And Wifi. Automatic Locking. USB Emergency Power. Alexa And Google Assistant Supported. Reversible Right And Left Function. Waterproof Rubber Plate Suitable For Exterior Use. Body In Aluminium And Stainless Steel 304 Alloy. Locked/Unlocked Speaker Voice Nofication In English Or Spanish. No Wiring Required For Installation, Operates With 4 AAA Alkaline Batteries Not Included. Fits Stanadrd Back Set From 2-3/8 in. (60 mm.) to 2-3/4 in. (70 mm.).