This TeacherGeek Mini Hub is designed to slide directly on to a 5mm dowel. It is comprised of two parts that are held together with a single screw. This allows you to secure 2, 3 or 6 turbine blades. When the hub is mounted on to a dowel that is allowed to rotate (as in our Wind Lift Activity) work may be accomplished. Small blades may also be used for boat propeller applications.