When buying an anemometer the main concerns are accuracy, build quality, portabilty and ease of reading. There are 2 types of propeller, cheaper units will use a propeller that must face the wind precisely in order to obtain accurate readings, whereas higher end units will have a direction independent propeller. Cheaper units tend to have harder to read displays and be very sensitive to the wind direction. However if held correctly they can give good results. For a quality at a low price we highly recommend the Benetech LCD Digital anemometer and for professional use take a good look at the JDC Atmos anemometer.