The blower is supposed to be capable of 100 MPH. When I put the concentrator on and check it with my anemometer, it reads about that. I wasn't interested in 100, I was more concerned with the 40 - 60 range. Set up the blower to get close to 45 at the pitot tube. It was fluctuating around 45 (42 - 47). When I checked the Airspeed indicator it was bouncing between 42 & 47 so I called it close enough. Went up and performed the same steps at 55 & 65 with similar results. I'm comfortable that the airspeed is accurate at the low speeds around the stall.