GHP Black Adjustable Chimney Cap Fits Most Chimneys Sizes Fits Flues with outside dimensions: 8" to 13" wide by 13" to 16" long. This will do 8 x 13, 13 x 13, 13 x 16. Adjustable brackets turn around to adjust to chimney size. Heavy Gauged Steel Power coated paint in satin black. Easy installation No tools need to install. Keeps out birds, rain, squirrels, leaves.