The Dwyer 9671 thermo-anemometer is a multifunction instrument that measures air velocity, air volume, temperature, humidity, and BTU. The unit includes a large 1.8" (45 mm) display which allows users to easily view readings. The vane style anemometer can measure in user-selectable wind speed units including ft/min, m/s, knots, mph and km/hr. In addition to these functions, the 9671 is capable of measuring relative humidity, wet bulb temperature, dew point and BTU capacity. A built-in sensor records ambient temperature in °F or °C. Features of the 9671 include data hold, along with the ability to record minimum, maximum and average readings on a single point. Additional features include an RS-232 interface setting that allows the unit to download data, as well as upload up to 99 measurements through pre-edited PC files. The 9671 also has a detachable probe for easy replacement, if necessary, or to attach a miniature vane probe.