TECHKO’s Magnetic Sensor Alarm can provide valuable protection for your home or property by detecting unauthorized opening of a door, sliding window or cabinet door with a 6-tone alarm. This magnetic sensor alarm can be mounted on almost any door or window and requires no wiring or special installation. The magnetic sensor can be placed on either side of the unit as long as the arrows are pointing towards one another. Requires (3) 1.5V AAA batteries (not included), contains one Magnetic Sensor Alarm.