The Model VP2 Wireless 100 mm Vane Thermo-Anemometer Probe measures air velocity, air flow, humidity, and temperature when combined with the Model UHH2 Universal Handheld. By having a larger diameter, the rotating vane is able to measure velocities down to 50 fpm or 0.25 m/s. An arrow is molded into the vane housing to depict the flow direction.