Extech 407113 CFM Metal Vane Anemometer Metal vane withstands temperatures up to 175?F and airspeed up to 7880 feet/minute Displays air flow (CFM) or air velocity (feet/minute) plus temperature on dual display Choice of readings in feet/min, meters/second, kM/hour, MPH or knots Air flow displayed as instantaneous value, 2/3 value or 20 point average Min/Max function