ANEMOMETER Great for outdoor activities! The Anemometer is useful in determining wind speed. Made of corrosive resistant materials for prolonged outdoor use. One cup is colored red for ease in determining the number of rotations. The anemometer Is a simple device used to determine wind speed. It is simple enough for elementary children to understand and use while accurate enough to be used by professional meteorologists in weather forecasting. The unit consists of a post with revolving wind cups. These cups are each mounted on horizontal arms which extend from the axis of rotation. Make sure that each cup is pointed in the same direction with its face perpendicular to the ground. The unit measures 220mm x 160mm. Instructions provided. (9" x 6-1/2" x 9"; .27lbs).