Amazon.com: Aeco SI18-C5 PNP NO H, Inductive Proximity Sensor, 18 mm Diameter, 10-30 VDC, 3-Wire, PNP : Industrial & Scientific
Amazon.com: Taiss 2PCS M12 4mm Sensing DC 5V NPN NO(Normally Open) 3D Printer LJ12A3-4-Z/BX-5V Cylinder inductive Proximity Sensor Switch Work Voltage 5VDC Special for MCU : Industrial & Scientific