The Ring Contact Sensor for Window & Door 1st Gen is a white, battery-operated anti-theft device designed to detect when a window or door is opened. Made of plastic, this compact sensor has a diameter of 2.5 inches and is easy to install without the need for any tools. With an operating sound rating of 130 dB, this unit from Ring is a reliable addition to your home security system, providing peace of mind and protection against intruders.