The REED Sling Psychrometer is designed for portability and has a slide rule construction that quickly converts temperature to relative humidity. Its built-in reservoir holds sufficient water for several hours of testing and the thin bulb design gives fast thermal response. It features a non-mercury red spirt filled thermometer and the thermometer is constructed of shock-resistant glass; stems have deep-etched numerals and 1" scale division for easy reading. This psychrometer is ideal for measurement of comfort conditions in air conditioned environments, hospital operating rooms, storage areas and laboratories.