Grade: 2 Model: D75BNO D75BNO is a standard Grade 2 surface contact. The D75 is a standard surface contact complete with an internal PCB and wire clamping terminal blocks. 2 terminals govern the switch, 2 provide a tamper loop and the remaining two are left as spares. Terminals are marked on the PCB for ease of installation. This is a rectangular contact with smooth, rounded edges. it provides an operating gap of approximately 35mm. Both contact and magnet are 78x24x20mm. 6 wire clamping screw down terminals are provided on the PCB – two for the switch, two for tamper and two unlinked spares. The tamper on this contact is provided by a sprung microswitch, which will detect removal of the lid. This contact is Normally Open (N/O) – The circuit through the contact is complete until the magnet is moved close by. With the magnet in close proximity, the circuit through the contact is broken. Supplied with fitting screws.