The Kestrel 3500DT Delta T Weather Meter takes all the great features of the Kestrel 3500 and adds in one additional reading, Delta T - the spread between the wet bulb temperature and the dry bulb temperature (in degrees C). Delta T offers a quick guide to determining acceptable spraying conditions. For example, it is not recommended to apply pesticides when Delta T is above 10 - a range of 2 to 8 is ideal. With the Kestrel 3500 Delta T Weather Meter, the calculation is done for you, accurately and simply. The Kestrel 3500 DT incorporates barometeric pressure correction in its wet bulb temperature calculation, ensuring accuracy even on low pressure days, at high altitudes, and in the very dry weather when Delta T monitoring is important. No other pocket weather meter offers this feature with this level of accuracy. KESTREL 3500DT MEASURES: Delta T / Current Wind Speed / Max Wind Gust / Average Wind Speed / Air, Water, and Snow Temperature / Wind Chill / Relative Humidity / Dewpoint / Heat Stress Index / Barometric Pressure / Altitude / Wet Bulb Temperature. KESTREL 3500 DT FEATURES: Real-time clock / Protective cover with sure-grip overmolding / Data hold function / Large easy-to-read display with backlight / Waterproof and floats / Measure environmental conditions quickly and accurately / Forecast weather with pressure trend indicator / Reliable, portable and easy to use / Innovative humidity sensor designed for stability and accuracy in abrupt condition changes / Thermally adjusted humidity sensor / Patented user-replaceable impeller / Quick response, external thermistor / High precision pressure sensor / User calibratable humidity sensor (requires optional RH Cal kit). The Kestrel 3500DT Delta T Weather Meter Includes Slip on protective cover, neck lanyard, CR2032 cell battery (avg. life 300 hours). Also includes Kestrel Certificate of Conformity. All Kestrel weather instruments are MADE IN THE USA. 5 Year Warranty. Normally ships in 1-3 business days. MSRP: 269.00.