Doors and windows as the entrances and exits are the weakest points of your home. An unsecured door or window is like an obvious “WELCOME” sign, to a burglar, so door/window sensors are also known as “entry sensor”. As one of the most popular home security devices, DW2-RF wireless door/window sensor is enough smart to get you to know whether your door or window is open, and it can not only send you alert notifications, but also make you know when the entrance point is opened, making sure your home is safe.         More importantly, the sensor allows you to add  or old smartphone to view who is entering your home, providing you with more details and notes about the uninvited guest. Can sync the opening and closing status of door/window to app which gives you a peace of mind when you’re not at home. History records check can be traced back to the last 3 months and this can help you look back and check the condition of your home at that time. Lights are triggered in the action. You can set the linkage in the smart scene of the eWeLink app to connect the sensor and your light so that you can open or close the door to trigger the hallway light on and off. The  is required for making this linkage possible. Combines with IFTTT service, the sensor can be used to trigger more devices or routines. This “device sharing” feature is for letting more of your family know your home is secure. After sharing the sensor, all of the shared users will receive the alert about the condition when someone opens the door. The sensor is 3M adhesive installed, easy to move and remove. It can work just fine upside down and sideways, as long as the magnet is less than 5mm from the sensor, which makes no difference how the sensor is located. It’s battery operated and has a low power consumption that ensures the battery life can last up 2 years.       Send the alert to your smartphone when the door/window is opened     Open and close the door to trigger lights on/off     Sync the opening and closing status of window/door to app     Compatible with IFTTT service to set more routines     Share the sensor to make more users know the status of home     Can check history records last 3 months     Low power consumption technology maximize the battery life - up to 2 years     Easy to install and remove       Overview             Specifications: Working Voltage: DC12V (Model: 27A 12V); RF: 433MHZ; Emission current: ≤ 20 mA; Quiescent current: ≤ 1.5 uA; Wireless Transmission distance: Max. 50m; Material: PC V0; Package Included: 1*SONOFF DW2-RF - 433MHZ RF Wireless Doo Notes: Note: SONOFF DW2-RF doesn’t come with batteries into package.