Rockford Chimney Supply Stainless Steel Chimney Cap, Single Flue Tile Mount 13x18 Inch Fits outside chimney tile dimensions 12" x 17" to 13 1/2" x 18 " Rockfords stainless steel chimney caps will never rust Easy chimney cap installation for do it yourself homeowners Installation support before and after the sale; we're here to help you do it yourself Removable chimney cap lid for easy cleaning and inspection