This Is An X-Long Propeller Adapter Nut from Dave Brown Products. FEATURES: Plain Black, CNC machined steel construction. Use with 3-1/4" to 4" spinners. 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 .61-.90, SuperTigre .61-.90 and G2300 Fox .60-1.20 INCLUDES: (1) Propeller Adapter Nut (1) Propeller Washer REQUIRES: 1/2" Wrench Spinner Cone & Bolt Backplate Propeller SPECS: Crankshaft Thread Size: 5/16-24 Nut Length: 1.625" COMMENTS: 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. JAL 4/28/99 ir/jl kr2/26/03