The Kestrel Meter 5500FW Heat Stress Meter measures/features

• PIG Screen (Probability of Ignition) 
• FDFM Screen (Fine Dead Fuel Moisture)
• Waterless! Natural Wet Bulb Temperature accurately calculated from on-board digital sensors with no tedious setup or maintenance.
• Large, hi-res, hi-contrast, graphic display is perfectly readable in the brightest sunlight and is backlit for use in low-light conditions.
• Globe Temperature
• Naturally Aspirated Wet Bulb Temperature
• Wind Speed (Current, Average, & Maximum)
• Altitude
• Pressure trend
• Barometric pressure
• Relative humidity in %
• Accuracy:  +/- 2%RH
• Sensors:  10 to 90% 25°C non-condensing
• Calibration Drift: Typically less than +/- 0.25% per year!
• Heat stress index
• Dewpoint
• Wet bulb temperature
• Density altitude
• Wind chill
• Air, water, and snow temperature °F or °C
• Waterproof
• Time and date
• Easy- to-read backlit display
• Data Logger (automatic and manual)
• Customizable data storage - 2900 data points
• Humidity sensor can be calibrated in the field with our Relative Humidity Calibration Kit.
• Customize screens to display user-selected measurements
• Graph and recall trends
• User-replaceable impeller
• Data charting
• Upload to a computer (with optional interface)
• Meets MIL-STD-810F 516.5 Procedure IV Transit Shock test - 20 drops from 5 ft. IP-67 sealed to exclude dust and water at 3 ft. submersion
• Five languages (English, French, Spanish, German, and Italian)
• US Patent Nos. 5,783,753 and 5,939,645 and 6,257,074
• Made in the USA
• 5 Year Warranty

Calibration:

RH (Relative Humidity):  See Chart for more detail.

• Accuracy:  +/- 2%RH
• Sensors:  10 to 90% 25°C non-condensing
• Calibration Drift: Typically less than +/- 0.25% per year!