the prop is for Haibo motor of 2.5" O.D.(18lb) ,It is specially designed for improving the work efficiencyLooking for ideal Three Blades Propeller Manufacturer & supplier ? We have a wide selection at great prices to help you get creative. All the Propeller with Three Blades are quality guaranteed. We are China Origin Factory of Prop with Three Blades. If you have any question, please feel free to contact us.