The Kestrel 2500 Handheld Weather Meter measures wind and temperature with total accuracy, and has the added benefits of an air pressure sensor that provides altitude and barometric information. Kestrel 2500 technology enables you to follow changes in air pressure that help predict impending changes in the weather. Factor in the 2500's digital altimeter, and you have most of the weather information you need for outdoor activities ranging from model airplane flight to rifle practice. A quick compare chart of the basic models shows you the differences between several Kestrel models. As with all Kestrels, the 2500's sensitive and user-replaceable impeller technology provides accurate wind speed info. Additionally, an external temperature sensor and waterproof casing allow you to gauge the temperature of water and snow, as well as the open air. A hard slide-on case, lanyard, and battery are included.