Model Size Fits Minimum Inside Flue Sizes Fits Maximum Inside Flue Sizes
8" x 8" 6" x 6" 9" x 9"
8" x 17" 6" x 14" 9" x 17.5"
9" x 13" 7" x 9" 8" x 12.5"
13" x 13" 9" x 9" 12.5" x 12.5"
13" x 18" 9" x 14" 12.5" x 17.5"
18" x 18" 14" x 14" 17.5" x 17.5"