Abus opening detectors 24 core white 2m4m5m abus fu7350w the abus fu7350w opening detector 2 core white 2m is a magnetic contact for protecting doors and windows any unauthorised opening is detected and reported to the alarm centre the opening detector consists of a magnetic contact reed and a magnet which are fitted parallel in front of or at right angles to each other at a maximum distance of 13mm apart the electric circuit of this nc opening detector is normally closed nc if