These centrepieces are made from machined aluminium and provide the ideal yoke for your folding propeller. They have an 8mm hole which matches many types of prop adaptors and precision spinners, and the cheeks are 8mm apart to accept most folding prop blades.
The blades pivot on 3mm bolts with a smooth shaft to allow smooth swivelling, and which also come with nylock nuts for firm attachment.
Remember, when working out prop sizes, that Aeronaut assume a 42mm centrepiece, whereas Graupner assume a 32mm centrepiece. You can vary prop size by varying the size of the centrepiece.
The -5 degree and +5 degrees centrepieces also vary the pitch by about 2 inches, so you can vary the pitch by using these centrepieces.