Entry sensor - Protect your doors, windows, cabinets and more. Compact design - Fits on almost any window, door or cabinet. Instant chime alerts - When a door or window is opened, the Base Station can sound a chime or tell you which sensor has been activated. Customizable alerts by sensor - Can set up Secret Alerts that wont sound the alarm but will send a discreet notification directly to your phone. Simple set up - Peel and stick installation or can permanently mount with included hardware. Long-lasting battery - pre-installed battery Compatible with the SimpliSafe Gen 3 home security system Pro Tip: Can be customized to send secret alerts so you can be quietly alerted if someone accesses private areas without sounding an alarm.