This is Active Infrared Detector.Install each pair at the opposite positions.Then there is a
infrared area between these two detector parts. When someone passes the infrared region, the detector
will send alarm signal to the security alarm host (which not included here).
* Install Distance(Max.)in the above chart means the maximum install distance between the two
* Great to be installed for security system in school, office building, hosipital, home yard, etc.
* Detecting range can be reduced to 30% in bad weather conditions, like rain, dust, etc.
* English Usage Manual included in the pack. It will give you detailed instructions