It appears to be off the market now but it mounted the existing prop blades further out, giving a wider prop diameter and so gave brilliant low-down grunt to get you up out of the water. The prop diameter is 15cm, 16cm and 17cm for the 2-blade, 3-blade and Magic Hub prop hubs.I found the difference between the 2-blade and MH to be astounding! I asked on the Facebook group if there was much difference between the MH and 3-blade, which came out sometime later, and was told that the 3-blade was a bit better. I used the 3-blade once and felt that I was simply spinning my tyres by comparison and sold it.