I'm confused. The DA-100 comes with a 6-bolt aluminum prop hub. It takes 6 bolts to attach the prop to the hub. Then there is a 7th bolt that threads into the center of the hub that hols the spinner on. This 7th bolt does not hold the prop on. The 6 bolts that come with the engine are typically long enough for attaching any brand of 27 or 28 inch prop (wood or Carbon).