This is a Vortech 5" Aluminum Two-Blade Spinner from Dave Brown. FEATURES: Light-Weight Aluminum Construction Polished, Brushed Aluminum Color Includes Four Plastic Backplate Bushings, So The Backplate Will Fit Securely Around Any Ordinary Crankshaft Designed for Two-Bladed Props INCLUDES: One Two-Blade Aluminum Spinner (For Sizes See SPECS) One Aluminum Backplate One 10-32 x 1-3/4" Cap Head Mounting Bolt Four Plastic Backplate Adapter Bushings One Instruction/Information Header Card REQUIRES: Vortech Adapter Nut (See COMMENTS) 4mm Allen Wrench (For The Cap Screw) SPECS: Spinner Backplate Diameter: 5" (127mm) Spinner Backplate Mounting Ring Thickness: 3/16" (4mm) Spinner Backplate Hole Diameter: 3/8" (9.5mm) Length From Back Of Backplate To Front Of Cone: 4-15/16" (125mm) Weight: 8.1 oz. COMMENTS: To Attach the Spinner to the Engine, the Modeler Must Use One of the Following Adapter Nut Sets. Note: Use A Short Adapter With Spinners 2-1/2" And Smaller. Use A Long Adapter With Spinners 2-1/2" And Larger. Use A X-Long Adpater With Spinners 3" And Larger. 3/8-24 DAVQ9324 (Long), DAVQ6324 (X-Long) OS Max 1.08 FSR, FT-240, FT-300 and FR-300, K&B 1.00, Magnum XL-180AR, Enya VT-240 Twin 1/4-28 DAVQ8428 (Short), DAVQ9428 (Long), DAVQ6428 (X-Long) OS Max .25-.60, SuperTigre .25-.60, Fox .19-.50, Enya .25-.53, K&B .19-.65, OPS .40-.60, Webra .28-.80 5/16-24 DAVQ8524 (Short), DAVQ9524 (Long), DAVQ6524 (X-Long) OS Max .61-.90, Supertigre .61-.90, Fox .60-1.2 7x1.0mm DAVQ8710 (Short), DAVQ9710 (Long) Enya .35-.60, .60-1.2 Four Strokes (Non-R Engines) 8x1.0mm DAVQ8810 (Short), DAVQ9810 (Long) YS .90-1.2 4-Stroke, Enya 1.2R 4-Stroke, OPS Super .60 and .61 5-Port 8x1.25mm DAVQ8812 (Short), DAVQ9812 (Long), DAVQ6812 (X-Long) All YS 2-Stroke, OPS Maxi .30, Webra .61-1.2 It Is Best To Use The Longest Adapter Nut That Will Fit. JAL 4/27/99 ir/jl