The N505A-STHSMPAG from Nascom is a gate contact with magnetic Pull-A-Part switch, 3' armor cable, black. The N505A/STMPA Magna Pull is the most durable on the market today. There are no plastic parts to break. Magnets won't fall out of the housing and the switch won't bend or break. Our magnet housing is bar stock aluminum and the switch housing is tubed aluminum filled with epoxy protecting the reed switch in side. This switch is used for protecting gates of all types and commercial trailers connected to distribution warehouse dock alarm systems.