Shaft extensions as required by some plans to facilitate fully cowling the engine.  We custom manufacture suitable units to give an extension of up to 35mm.  They are specially designed to grip the prop driver using a nylon facing and attachment is provided for a spinner backplate if required.  The engine/shaft size and thickness of prop/backplate should be specified on ordering so that the sleeve nut can be made of the correct length.  These are supplied at the customers own risk as improper use can result in engine/airframe damage.