Smart lock with built-in bridge, fits into the existing cylinder and key on the inside of the door, and allows you to open and close with an app on your iOS or Android smartphone (communicates via bluetooth v5), is compatible with with Apple HomeKit, Hey Google and Alexa. Includes Power Pack with rechargeable NiMH batteries. Specifications: Product: Smart Lock Pro Color: Black Weight: 580 g Dimensions: 110 x 60 x 60 mm Power Supply: Nuki Power Pack included (Rechargeable NiMH battery pack) Communication Technology: Bluetooth 5.0, WiFi Prerequisites: iOS or Android Smartphone