Every Rubex aluminum boat propeller has a rubber interchangeable hub system. It is designed to eliminate chatter and vibration that competitive hub systems are prone to. Being rubber, the Rubex hub has no plastics to deteriorate. It can deflect 10% for softer shifting and to reduce propshaft shock when the propeller strikes a submerged object. The Rubex hub will not spin in the propeller. 15.5" Diameter. 13" Pitch. Right Hand Rotation.