Hand powered relative humidity measuring device (%RH) .Rotate to provide adequate and consistent ventilation of the bulbs.Environmentaly friendly blue thermometer tubes with LO-tox™ filling.Similar accuracy as mercury but with clearer legibility.Range: -5 to +50°C.Accuracy: +/- 1°C.Resolution: 0.5°C.Dimensions closed: 82 x 232 x 30mm.Supplied with 2 replacement wicks, carry case and calculator chart.Refill tubes available on request.