Entry Sensor Protect Your Doors and Windows from Break-Ins with eufy Security Entry Sensor. Once a window or door is ajar by 1.5 inch, an alert will be sent to your smartphone, and a 100-decibel siren will go off on the HomeBase (can be disabled). Requires eufy Security HomeBase. eufy Security: Less Trouble. More Secure. Ever Expandable. Surveil your home from front to back for total peace of mind Created by the same team as Anker: renowned for exceptional quality and innovation FAQ 1. Is there any battery included in the package? Yes, a CR123A Battery is included. 2. Can I use my own router to pair with eufy Security Entry Sensor? No, you can only use eufy Security HomeBase to pair with eufy Security Entry Sensor. 3. Can I use it in an outdoor environment? No, it is designed for indoor use only (Not Weatherproof). 4. How can I know if I need to change the battery? There’s low battery life notification, which will inform you when the battery level is lower than 10%. 5. How to install the entry sensor? Step 1: Peel off the mounting tape and stick or screw the sensor onto the door or window you want to monitor. Step 2: Stick the magnet part onto the frame of this door or window near the entry sensor’s printed “Magnet” wording. Note: Please make sure the distance between entry sensor and the magnet is shorter than 1.5in.