BQLZR Golden 2mm-3mm Brass Joint Motor Shaft Coupling Adapter Connector for RC Aircraft Pack of 2 Ideal accessories for RC Model motor, such as airplane boat model. Widely used in metal, mold, mechanical drive applications. Between the transmission member can do both screw can do model remote control boat propeller shaft and the motor power. Connecting two axis with different diameters, can also be connected with a motor axis, or connecting shafts of different diameters.