The BEAMLRK allows reflected beam detectors to be installed at separations between 230 and 328 feet (70 to 100 meters). At these distances, four 8? ? 8? reflectors must be used to provide enough reflected infrared light. This kit includes 3 additional reflectors with new test scale legends. The reflector included with the transmitter/receiver unit is the fourth reflector to be used. This kit is not compatible with the multi-mount kit (BEAMMMK).