Without a doubt, the main advantage of this handheld cup vane environmental tester is that it doesn't need to be held exactly in the direction of the wind. Environmental tester with impellers typically have to be held exactly in the direction of the air flow to take accurate measurements. However, this cup vane environmental tester's system is so sensitive that it responds to the smallest of air currents. To perform a correct measurement with the cup vane environmental tester: First turn the meter on, then hold the meter vertically so the cups can rotate until the wind velocity is displayed. In the following picture you can see how to measure wind speed with the cup vane environmental tester. 

As previously stated, different measurement units can be selected with the cup vane environmental tester: m/s, km/h, knots, ft/min and mph. To change measurement units in the cup vane environmental tester, you must press the key Data Hold until the desired unit is displayed, then depress the key. You can save the unit in the memory of the cup vane environmental tester to be displayed every time the meter is turned on. If the messages Hold or REC appears in the display, you cannot change the measurement units. Moreover, you could fix a value in the cup vane environmental tester by pressing the Hold key during the measurement. To deactivate this function please press the Hold key again.