Extech 45158 mini anemometer with temperature and humidity measurment extech 45158 the extech 45158 mini thermo anemometer is a pocket sized air velocity meter which also displays of temperature relative humidity and dew point the fold up protective housing extends to 229mm 9in for better reach flips open to show its lrge dual display of air velocity and temperature or relative humidity the anemometer can be dropped from 1 8m 6ft without damage and it even floats supplied with a neck