What is a Photoelectric Sensor? - Types - Features
fire alarms for home Smoke Detectors with Enhanced 10 years Photoelectric Sensor,optical smoke alarm for home with 5 Year Battery Operated for office ...
Smoke Detector 10-Year Battery with Test/Silence Button, AEGISLINK Fire Alarm with Photoelectric Sensor, Low Battery Warning, Complies with EN 14604, ...
Interlinked Mains Smoke Alarm Photoelectric Detector 240V Battery Back Up Linked | eBay