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.  

Features:
[Ensure Your Home's Security] Remind you when the door/window is open and closed. A 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. 
[Sync to App] Sync the opening & closing status of door/window on APP. 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. 3-month history records check. 
[Connect with Wi-Fi Devices] Can make ZigBee and Wi-Fi devices keep linkage. The sensor provides you the possibility to create a scene linkage of ZigBee and Wi-Fi devices. 
[Light Control] Control the light with an action. 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. 
[Work with Camera] Support adding the SONOFF camera to view what happened at your home. 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 don’t keep watch on it. 
[Share Control] Share control makes other users control the connected device quickly. Share the sensor with your family to give them an ability to quickly control and monitor your home together. 
[Low-battery Notification] The unit is battery-operated that your mobile phone will receive a low-battery notification when the remaining battery level is less than 10%, maybe it's time to change the battery. 
[Easy Installation] Simple peel and stick installation. Peel and directly stick it on the targeted place or object, a smart security system is ready for you.  

Note:
*ZigBee Bridge is required, and it is sold seperately. 
*The device can work with other gateways supporting ZigBee 3.0 wireless protocol. 
*camera is not included. 
*Battery is not included.  

Specifications:
Material: PC; 
Battery: 3V (CR2032); 
Wireless Connection: ZigBee 3.0; 
Maximum Working Distance: 80 meters(without obstruction); 
Item Size: 4.7*2.7*1.35cm / 1.85*1.06*0.53in(sensor); 3.2*1.56*1.3cm / 1.25*0.61*0.51in(magnet); 
Item Weight: 14g / 0.49oz(sensor); 6g / 0.21oz(magnet); 
Package Size: 4.8*4.5*1.8cm / 1.88*1.77*0.7in; 
Package Weight: 25g / 0.88oz;  

Packing List:
1 * Wireless Sensor; 
1 * User Manual(Multilanguage); 
1 * Double-faced Adhesive Tape