Celestron WindGuide Anemometer is a small, handheld way to measure wind speed over a period of time. These incredibly useful Celestron weather instruments are simple to use and can measure wind speeds up to 65 mph, displaying real time wind speed, max wind speed, and the average speed over the period of measurement. When the temperature falls below freezing (as indicated by the WindGuide's current temperature readout), the Celestron Wind Guide Portable Anemometer will also calculate wind chill. Celestron has equipped the WindGuide with a bright blue back light that helps you to read the weather instrument in total darkness, and its rubber cover and weather resistant construction protects it from impact and environmental hazards. Due to its speed, durability, and accuracy, the WindGuide weather instrument is useful for a plethora of activities, including kayaking, snowboarding, parasailing, wind surfing, construction, sniper training, technical measurement for air conditioning units and computers, and almost any activity that is affected by or encounters wind. The perfect outdoor companion whether it's blustery or calm outside, the Celestron Wind-Guide Beaufort Scale Anemometer is a useful tool that fits right in your pocket.