This WindScribe meter is incredibly useful if wind speed is a factor. For boating, fishing, working outside, or just having fun. You hold it up so the wind blows through the "tunnel" on top and it displays the wind speed in metric or U.S. units. Beats trying to gauge the wind using a wet finger! Senses breezes as low as 0.4 mph or as high as 150 mph. Displays a 5 second average wind speed, running avg, max, and min speeds. Also displays current, max, min, and average temperature. No moving parts. Powered by a 2032 coin battery (included).