Description: The wireless door/window sensor is essential for knowing who is coming in and out of your home, so it is most often used as part of smart security system. SONOFF SNZB-04 is a ZigBee two-in-one wireless door/window sensor that can be put on your door or window to tell you with an alert notification if your door or window is opened or closed, adding an extra layer of security to your home. The sensor provides you the possibility to create a scene linkage of ZigBee and Wi-Fi devices. Both the opening and closing status of the door/window are synced on your mobile phone, no longer to think back whether the door/down is off or not. It is really useful and can help you turn on or off the light in the action. Works with SONOFF ZigBee Bridge in harmony, you can set a scene to get your hallway lighted immediately when the door is opened. The camera function can be enabled on the sensor page in the eWeLink APP, which also allows you to view clearly who enters your home; even you can frighten the stranger and ask him to leave your home immediately with the two-way audio function. Its application can also extend to wide areas like drawers, garage doors, blinds, etc. Just stick it anywhere two things connect and it is always safe even if you dont keep watch on it. Share the sensor with your family to give them an ability to quickly control and monitor your home together. Simple installation for easier setup. Peel and directly stick it on the targeted place or object, a smart security system is ready for you.