This compact Sling Psychrometer accurately determines percent relative humidity without the necessity of consulting complex tables.

• Designed for portability (7½" long x 1" diameter)
• Slide rule construction quickly converts temperature readings to relative humidity
• Built-in water reservoir holds sufficient water for several hours of testing — no need to wet a wick
• Thermometers constructed of shock-resistant glass; stems have deep-etched numerals and 1° scale divisions for easy reading
• Thin bulb design gives fast, thermal response
• Accurate to within ±5% RH
• When not in use, the thermometer case telescopes into the handle for protection