Amazon.com: Non Contact Liquid Level Sensor Contactless Water Tank Water Level Sensor for Tank Water Level Control PNP/NPN(XKC-Y26-NPN) : Industrial & Scientific
Slim DIN Rail Mount NPN to PNP/PNP to NPN Sensor Logic Signal Converter Module: Amazon.com: Industrial & Scientific
Amazon.com: YXQ 25mm PNP NO Capacitive Proximity Sensor Switch DC6-36V 300mA 3-Wire 3 Meter Lead : Industrial & Scientific
Amazon.co.jp: Approach Sensor DC PNP 3-Wire Induction Proximity Switch 5mm Detection Distance Normal Close Proximity Sensor Switch SN04-N2 : Industrial & Scientific
Amazon.com: Baomain Capacitive Proximity Sensor Switch LJC12A3-5-Z/AY PNP NC DC 10-30V 200mA 1-5mm Blue : 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