The Extech 407113 CFM Metal Vane Anemometer measures Air Velocity from 100 To 6890 ft./min, 0.5 To 126 m/sec, 1.8 To 126 km/hr, 1.1 To 78.3 mph, and 1.0 To 68 knots with an accuracy of +/- 2% Of Velocity. Meter also measures 0 to 999,900 Cubic Feet Per Minute, 0 to 999,900 Cubic Meters Per Minute, and Temperature from 32 To 175 F/0 To 80 C. Anemometer features Min/Max, Data Hold, Auto Power off, and a built-in RS-232 interface with optional Data Acquisition Software.