The GRI 4700-A series industrial track mount switches are designed to eliminate false alarms from standard floor switches getting damaged by fork lifts and other equipment. The contacts are moved up onto the track and out of the way of equipment.The 4700-A series switches are designed to be easy to install and very adjustable. They can attach to a wide range of track sizes and only require tightening one or two screws to install the contacts. It can be installed on either side of the door and the cable exit can be reversed to simlifiy installation.An adjustable magnet bracket extends the reach on particularly difficult installations and self drilling screws shortens installtion times. Also with a gap of up to 3 inches, doors that wear and get misaligned are not a problem Also known as -G.R.I. Telemark Corp. TRACK MNT SWITCH SET 3 GAP - GI-4700A