The MSS100-19 BMS High Security Magnetic Contact is a 3 3/4″ long heavy duty surface mount contact that works on steel doors where an industrial contact is preferred. This magnetic contact has one CC door switch and one OC magnetic tamper switch when magnet is present as well as a internal coil for remotely testing switches. There are five color coded wires and a surface mount rare earth magnet. Armored cable, 18″ long, and epoxy sealed electronics make it impervious to harsh environments. Provide your customers more than just a door switch, give them time tested inexpensive Flair high security contacts with built in magnetic tamper.sonable price.