Feature:1. DW2 Wi-Fi comes in two pieces, the transmitter fits onto the door or window and the magnetic switch attaches to the frame. It can help secure your door or window to let you know whether your home is safe wherever you are. The sensor will trigger an alarm to your smartphone to remind you of an intruder when the door or window is opened.2. Keep linkage with smart devices to create various smart scene, turn on/off your light with an action.3. Notify you when the door/window is opened, and you can check the opening/closing status and history record of door/window on APP.4. No gateway required, BT low energy pairing. Allow sharing the sensor with your family to monitor and control of your home.5. Real-time battery level display and low-battery reminder ensure you get clear know how long the sensor can run and when you need to replace batteries.6. With simple peel and stick installation, it is easy to fit in door frames and window sills.Specification:SONOFF DW2 Wi-Fi comes in two pieces, the transmitter fits onto the door or window and the magnetic switch attaches to the frame. It can help secure your door or window to let you know whether your home is safe wherever you are. The sensor will trigger an alarm to your smartphone to remind you of an intruder when the door or window is opened.Features:Keep linkage with smart devices to create various smart scene, turn on/off your light with an action.Notify you when the door/window is opened, and you can check the opening/closing status and history record of door/window on APP.No gateway required, BT low energy pairing. Allow sharing the sensor with your family to monitor and control of your home. Real-time battery level display and low-battery reminder ensure you get clear know how long the sensor can run and when you need to replace batteries. With simple peel and stick installation, it is easy to fit in door frames and window sills.Note: *DW2 doesn't come with batteries into package.*The sensor can work for up to 3 months if the door/window is opened or closed three times a day.*1. The device only works with 2.4GHz WiFi.2. If the router is working in dual-band (2.4GHz & 5GHz), please upgrade the eWeLink app to V4.0.0 or higher.3. The pairing will fail if a wrong WiFi password is input.4. The device shall get close to the smart phone for a good transmission signal condition while pairing.Specifications:Model: DW2Material: PCBattery Type: 2pcs AAA battery, 1.5VWorking Voltage: DC 3V (2 * 1.5V battery)Quiescent Current: ≤ 40AEmission Current: ≤15mAWi-Fi: IEEE 802.11 b 2.4GHzOperating Systems: Android 4.1 or later, iOS 9.0 or laterInstallation Gap: <5mmWorking Temerature: -10~40Item Size: 7*3.1*1.9cm / 2.75*1.22*0.74in; 4.2*1.6*1.4cm / 1.65*0.62*0.55inItem Weight: 29g / 1.02ozPackage Size: 7*4.8*2cm / 2.75*1.88*0.78inPackage Weight: 37g / 1.3ozPacking List:1 * Door Sensor1 * Adhesive Tape1 * User ManualPackage List:1 * Door Sensor1 * Adhesive Tape1 * User Manual