PHOENIX SOLUTIONS LANKA (PVT) LTD - PV 00202557 - 1. Can utilize this space (*1) for sensor mounting. Needs to verify the count accuracy with the frequency. As per specifications it is about 20 times /Sec. 1 2nd is the sensor distance (sensitivity), needs to setup the sensor face for the most accurate position at the initial stage (most of the times this will be same for all the ventilators ). 2. When the object appears front to the face of sensor the display will give the appropriate count. Mahesh L. Premachandra 0716209087/0763183615