Low start-up wind speed, easily generate electricity through wind. Adopts quality motor, high efficiency and low noise, durable for long time use. The blade adopts strong nylon fiber with special surface spraying treatment, excellent. Double bearing is thick and not easy to shake when the machine is running. Good waterproof and sand resistance performance, can safely works in environment of.Material: Aluminum Alloy, Stainless Steel. Please allow 1-3cm error due to manual measurement, thanks for your understanding.