Amazon.com: HEXEH Proximity Switch Sensor Inductance Type Proximity Switch TL-N10MF2 Metal Induction Sensor 24V DC Three Wire PNP Often Close 10mm (Color : DC 3 Wires NPN NC) : Industrial & Scientific
Amazon.com: uxcell TL-Q5MC1 NPN NO Inductive Proximity Sensor Switch, 3 Wire, 6-36VDC, 5 mm : Industrial & Scientific
Amazon.com: Smart Caregiver Wireless Motion Sensor Alarm System with Pager for Fall and Wandering Prevention | Mountable Motion Detector Alarm Alerts Medical Caregiver with Up to 300' Range | Bed or Door
Baomain Inductive Proximity Sensor Switch TL-N20ME1 NO 20mm Distance DC 10-30V 3 Wire: Amazon.com: Industrial & Scientific
Amazon.com: 10PCS Inductive Proximity Switch, TL-Q5MC1 for 5mm Detection Metal Sensor DC 6-36V High Sensitivity for Metallurgy : Industrial & Scientific