Thie Sling psychrometer will measure humidity in your cheese aging room. To use it, you must be able to spin it while in the room to get an accurate measure of the rooms humidity. Cannot be used inside non-walk in refrigerators or freezers. Spirit-filled thermometer and holder telescopes into swivel handle. Sliding scale converts wet and dry bulb readings into relative humidity. The 20º to 120ºF thermometer with 1ºF scale divisions are 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.