The Caldwell CrossWind Professional Wind Meter was designed to be the best wind meter on the market for ballistic application. The 90 degree rotating anemometer head allows you to measure exactly how much CrossWind will be applied on the side of your bullet without ever having to move the wind meter or do angle calculations. This wind meter reads Current Wind Speed, Average Wind Speed, Max Wind Gust, Temperature and even Density Altitude, Altitude or Barometric Pressure. The included holster protects the wind meter and makes it easy to keep handy. It operates on one CR2032 battery(included).