This is a Two-piece Two-Blade White Nylon Spinner with a Nylon Backplate. INCLUDES: One spinner cone One backplate Two 1/8 x 9/16 S/T screws SPECS: Spinner Diameter: 3" Spinner Backplate Thickness: 3/16" Crankshaft hole: 1/4" (may be reamed to 7mm, 5/16", or 3/8") COMMENTS: Instructions state that this is a sport plastic spinner and not designed for use with high performance engines or engines with tuned pipes. Operation above 14,000 RPM is not recommended. NNA-6/14/94 ir/jl