Model 45158 packs a lot of capability into a pocket size meter that displays air velocity plus temperature or air velocity plus relative humidity on a large, dual display LCD. Wind speed values are displayed in 6 different units (feet/minute, meters/second, kilometers/hour, miles/hour, knots, and Beaufort) with +3% accuracy. Averaging for 2, 5, or 10 second intervals can be selected. Besides air velocity, it also measures wind chill plus relative humidity, and dew point. Features include data hold to freeze the most recent display and auto-power-off to preserve battery life. The 5-1/4 In. meter folds into a water resistant housing which is designed to float and withstand drops to 6 Ft. With the cover is open, the meter extends to 9 In. for reaching into openings. You will want to carry it with you whether you are on the job as an HVAC or plant maintenance technician or involved in recreational sports. Complete with CR2032 battery and 43 In. (1.09 m) lanyard.