Amazon.com: 2 Wire Normally Open Proximity Sensor, 50mm AC 90‑250V Proximity Switch Reflection Optical Photoelectric Switch Sensor for The Limiting, Counting, Positioning Control : Industrial & Scientific
4 Pack 120V AC Photoelectric Switch Light Control Sensor Button Switch with Automatic Illumination Detection Circuit,Dusk to Dawn Senso: Amazon.com: Tools & Home Improvement
Amazon.com: Obstacle Avoidance Photoelectric Switch, ABS Sensing Range Adjusting DC10‑36V Infrared Photoelectric Sensor for Robot for Automation : Industrial & Scientific
Photoelectric Switch with Accessories, Photoelectric Switch Diffuse Reflection Sensor Proximity Switch 24‑240V for Level, Photoelectric Sensor: Amazon.com: Industrial & Scientific
Photoelectric Switch, Long Service Life Retroreflective Photoelectric Sensor Switch Indoor Wall Mounted High Precision for Photoelectric Sensor: Amazon.com: Industrial & Scientific