M12 Inductive Proximity Sensor manufactured by Sky-Earth Sensor Co., Ltd. The product details are as follows:
Part Number: P1C1B1204PC3A2
Sensor Type: M12 Inductive Proximity Sensor, shielded
Sensing Distance (Sn): 4mm
Output: PNP-N.C. (Normally Closed)
Operating Voltage: 10-30VDC
Current: 200mA Max.