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 5CM diameter, presenting a 120-degree 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 2V. Its tolerance is about 10%.