Described as a windmill or a propeller anemometer,
this type of wind-speedmeasurement equipment has several vanes instead of cups. In addition,contrary to the Cup Anemometer, where the axis of rotation is vertical, its axis must be horizontal to parallel the direction of the wind. Similarly, the result depends on the rotate speed of shaft, which is recorded and converted to the wind speed by an electric chip. Under some circumstances, when the crosssection area is known to stay the same, the outcome can be more precise and satisfactory.