Celestron 48021 Windguide (Black) Wind speed measurement - measures current, maximum, or average wind speed Measures wind speed - up to 65 mph (90 Km/h) Wind measurement units - measures wind speed in m/s, Km/h, ft/min, Knots, or mph Wind chill indication - indicates wind chill when temperature falls below 32 F or 0 C Current temperature - measures temperature in F or C