PROFESSIONAL DESIGN: Unique anti RFI / EMI High Capacity Digital Filter Circuit design. Optical antiinterference Housing Professional. Four channel frequency adjustment function, suitable for stack installation in the same place. SCOPE OF APPLICATION: Widely used for alarm systems, access control systems, etc. Can be installed in schools, office buildings, hospitals, families, hotels, etc. Excellent Quality: Made of high quality plastic shell, eco-friendly, durable and sturdy to use. The plastic case has excellent characteristics such as corrosion resistance, easy cleaning and waterproof. When there is no external force, it is generally not destroyed, and the service life is very long. Receive a long range: create a reliable and invisible infrared beam up to 20 meters. By installing the receiver and transmitter at the same level, it can effectively detect and reach the alarm within 20 meters. Weather instructions: Thus, the infrared detector always has the ability to detect the distance when used in bad weather. The range can be reduced to 30% in bad weather: fog, rain, dust, etc.