Pit crews: make those last minute dial-in or tuning decisions count with the Kestrel 5100! Measure weather and conditions where it really matters - right at the track. The 5100 is a handheld portable weather station that tracks and logs time-stamped data you need like moisture content air density and relative air density (RAD). It also measures heading temperature (air/water/snow/wet bulb) barometric pressure wind speed (current/max/average) and direction cross/head/tail wind altitude pressure trend heat stress index dewpoint density altitude and wind chill. The 5100 features a backlit screen with night vision preserving light for bright sun or dark conditions. It s is also made for easy maintenance - no tools are required and the impeller is user-replaceable. The rugged design is fully waterproof and floats (IP-67) and is drop-tested to MIL-STD-810G standards. Track log and chart thousands of data points for optimum accuracy. Transfer data to your Mac or Windows computer via USB for storage and analysis (cable sold separately). The Kestrel 5100 is used by bracket racers drag racers pit crews and professional auto racing teams and provides you with the detailed information you need for the ultimate in race performance. Includes neck lanyard AA battery and protective pouch. The Kestrel 3500 is proudly designed and manufactured in the USA and is backed by a 5-year warranty.