BIM-IKM-AP6X2-H1141/S34 W/KLI-3 - 

Turck BIM-IKM Series Magnetic Field Sensors (AC Magnetic-field Immune)
The BIM-IKM series are activated by magnetic fields making them ideally suited for detecting piston positions in pneumatic cylinders. As magnetic fields can permeate non-magnetized metals, these units can detect the position of a piston with a permanently mounted magnet through the aluminum wall of the cylinder. They are made even more versatile thanks to having a wide voltage range of 10 to 65 Vdc. A yellow LED indicates the switching state making it easier to monitor. Weld-field immune permaprox sensors "freeze" the switching status when detecting a magnetic AC field (50 to 60 Hz). This prevents false switching operations during the welding process. The sensor will resume normal operation when the AC field disappears.