This is a wind speed sensor with a rain-proof design. It has a standard connector for Octopus brick series products. We can use it to test wind speed. It adopts three half-sphere bowls with a 6CM diameter, presenting 120 degrees branch installation. Under the effect of wind power, it can spin. The higher the wind speed, the faster it rotates. When the wind spinning component rotates with a diameter of about 20Cm, it will force a mini DC motor to generate DC voltage. Higher wind speed will generate higher DC voltage. Its maximum voltage generated can reach 1.2V. You can refer to the attached parameter form in the behind for actual wind speed and voltage output parameters. Its tolerance is about 10%. SPECIFICATION Item Parameter Height 9 cm Rotating Diameter 22 cm Chassis Diameter 57 mm Output voltage 0-1V Includes Octopus Wind Speed Sensor Anemometer Three Aluminium Cups - 1x Resources Wiki page