Pocket Slide-Rule Sling Psychrometer

No need to use tables or make calculations with this sling psychrometer for humidity monitoring. Spirit-filled thermometer and holder telescopes into swivel handle. Sliding scale converts wet and dry bulb readings into relative humidity. Protected by a strong plastic frame with built-in water reservoir to saturate wick. Feature magnifying front, deeply etched numerals, and thin bulb giving fast thermal response.