Magnetic field detection are activated by magnetic fields and are especially suited for piston position detection in manufacturer of pneumatic cylinders. Based on the fact that magnetic fields can permeate non-magnetizable metals, it is possible to detect a permanent magnetic attached to the piston through the aluminium wall of the professional cylinder. Magnetic-inductive permaprox sensors from TURCK operate on a patented function principle. Thus they are capable of reliably detecting permanent magnets of various field strengths on all common cylinder types. They operate completely wear-free and are short-circuit protected; a weld-field immune version for brazing applications is also available.