Colour Family: GREY Material: ALUMINUM Assembled Product Length: 12" Finish: ALUMINUM Assembled Product Width: 12" Diameter: 12" . Saves energy-operates with the slightest breeze Draws hot air from the attic in summer and moist air from the attic in winter Keeps your heating and cooling systems operating more efficiently Grey Multi-pitch base will even work on a 12/12 pitch 21 Vanes per unit 21 Top rivets 3/16" Rivets 1/2" Aluminum shaft Dual ball bearings 0.021 Aluminum for vanes 0.024 Aluminum for collar 0.024 Aluminum for base Baked enamel finish Dade County approved Maintenance free dual ball bearing system