Elgato Eve Door & Window
Elgato Eve Door & Window Wireless Sensor can sense whether your door or window is open or closed and share that data with the free app on your iPhone or iPad. It lets you see the current open/closed state at a glance and view statistics on time and duration so you're better informed.
Taking advantage of Apple HomeKit, Eve offers unparalleled ease of use and advanced security. Eve Door & Window connects directly to your iPhone or iPad using Bluetooth, so there's no need for a hub, gateway or bridge.