Kestrel 4250 features the best portable sensors available, assuring that it's dead-on accurate. Even slight changes in air density, water grains, and density altitude can dramatically affect a machine’s performance. With the added ability to easily measure and track these and other critical factors, such as absolute pressure, temperature, humidity, wind speed and barometric pressure, the Kestrel 4250 Racing Weather Tracker arms racers with the accurate weather data needed to make those last minute jetting or tuning decisions.