Emoloys the wet and dry bulb principle to determine % Relative Humidity.Designed to be rotated by hand, to provide adequate and consistent ventilation of the bulbs.This instrument has a folding handle and is supplied with a calculator chart and instructions to determine %RH and is provided in a protective canvas carry case.- Temperature Range: -5 to +50°C- Divisions: 0.5°C- Accuracy: +/-1°C