Model Size	Fits Minimum Inside Flue Sizes	Fits Maximum Inside Flue Sizes
8" x 8"	7" x 7"	10" x 10"
8" x 17"	7" x 15"	10" x 18.25"
9" x 13"	7" x 10"	10" x 13.5"
13" x 13"	10" x 10"	13.5" x 13.5"
13" x 18"	10" x 15"	13.5" x 18.25"
18" x 18"	15" x 15"	18.25" x 18.25"