Premium Quality Material: This Single Beam Photoelectric Detector is made of high quality plastic shell, which is eco-friendly, and sturdy to use 20 Meters Infrared Detector: This Photoelectric Infrared Detector can create a and invisible infrared beam up to 20 meters Widely Applications: This Photoelectric Beam Sensor Alarm has a widely application during daily life, it can be installed for security system, such as school, office building, hospitals, home yard, etc. Easy to Install: There comes with equipped screws for easy installation, and the half egg shaped can be easily and quick installed on the wall or door to protect your safety Note: Range can be reduced to 30% in bad weather conditions: fog, rain, dust, etc, Manufacturer: Walfront