Dave Brown adapter nut is constructed of plain black, CNC machined steel. Use with 3-1/4 to 4" spinners and under. This prop adapter kit tightens the backplate and propeller onto the engine, then using a single bolt-on design, holds and centers each spinner perfectly on its baseplate. Will fit the following engines: OS Max 1.08 FSR, FT-240, FT-300 and FR-300, K&B 1.00, Magnum XL-180AR, Enya VT-240 Twin.
Although it will depend on the thickness of your prop and the spinner size, as a general rule, always use the longest adapter nut possible.