abode's Recessed Door Sensor is perfect for people who want a completely hidden solution for detecting if your door is opened. The sensor and corresponding magnet are installed in the door and the frame and will report when the door opens and closes. Utilizing abodeRF, we designed the sensor to offer great battery life (up to 10 years under regular operating conditions) and range. The sensor requires a drill to install. The recessed door sensor is 3/4″ wide, 2 3/4″ long, and 3/4″ deep and comes in classic white.