The 21-inch propeller is made of Ultra Carbon Pro, an advanced composite material, for lower rotational inertia in combination with high strength and stiffness. One CW and one CCW prop, hubs included, 21 inches 2170. these hubs are not the same as the M600 2170, it may not fit M600. Props are assembled but need to be bolted to motor, washers, bolts, rubber gasket, and hardware included, black tape to hold screws in place until mounting.