This link includes both car intercom and top/bottom pit intercoms, available in two wiring configurations: four-wire and two-wire systems. The NBT12(1-1)B and NBT12(1-1)B1 are two-wire intercom devices, while the NKT12(1-1)B and NKT12(1-1)B1 are four-wire intercom devices. Please select based on your actual wiring needs.
