Monitor your home security with the ENER-J Smart Wi-Fi Wireless Door Sensor. This compact and elegant white sensor provides instant notifications to your smartphone whenever a door or window is opened, ensuring you're always aware of any activity. It's battery-powered with a long-lasting battery (approx. one year) and easy to replace. Setup is a breeze with plug-and-play functionality via the enerjsmart app – no hub required. Simply download the app on iOS or Android and connect. Perfect for remote home monitoring, this sensor adds a layer of smart security to your home without compromising on style. Product Summary: Smart Wifi Door Sensor, Wireless Window Contact, Smartphone Notifications, Battery Powered, Plug and Play, enerjsmart App Compatible, White, Extra Small.