Use this Garage Door Contact Switch on garage doors, roll-up doors and other doors or gates where it may be difficult to mount regular magnetic contacts. Smaller magnetic switches have a small operating gap where the contact and magnet must be within half an inch for reliable operation. While those switches are fine for most doors and windows in a home, they just won't cut it for larger doors. These contacts can be as far as 2" apart and still operate. These Garage Door Contacts for Closed Circuits are used for systems that expect a closed circuit when the magnet and sensor are together. When the magnet and sensor separate, the circuit opens. This set is commonly used with security systems. The sensor mounts to the floor and is made of a heavy duty polished aluminum die-cast housing. The contact switch is completely sealed with in this housing. On your door or gate, mount the magnet to complete the system. It is mounted on an adjustable L-bracket and is easily adjustable horizontally and vertically. A flexible 24" stainless armored cable protects the wires as they run along the ground.