Chim-A-Lator Damper Size(in)	Fits OUTSIDE Flue Widths of(in)	Fits OUTSIDE Flue Lengths of(in)	Lid Overhang(in)	Total Height of Damper(in)
8 x 8	7 - 9 1/4	7 - 9 1/4	2 1/2	10
8 x 13	7 - 9 1/4	11 - 13 1/2	2 1/2	10
8 x 18	7 - 9 1/4	16 - 18 1/4	2 1/2	10
8 x 20	7 - 9 1/4	18 - 20 1/4	2 1/2	10
10 x 18	8 - 10 1/4	16 - 18 1/4	2 1/2	10
12 x 12	10 - 12 1/4	10 - 12 1/4	2 1/2	10
13 x 13	11 - 13 1/2	11 - 13 1/2	2 1/2	10
12 x 16	10 - 12 1/4	14 - 16 1/4	2 1/2	10
13 x 18	11 - 13 1/2	16 - 18 1/4	2 1/2	10
13 x 21	11 - 13 1/2	19 1/2 - 22	2 1/2	10
16 x 16	14 - 16 1/4	16 - 16 1/4	2 1/2	10
16 x 20	14 - 16 1/4	18 - 20 1/4	2 1/2	10
18 x 18	16 - 18 1/4	16 - 18 1/4	2 1/2	10
18 x 21	16 - 18 1/4	19 1/2 - 22	2 1/2	10
20 x 20	18 - 20 1/4	18 - 20 1/4	2 1/2	10
20 x 24	18 - 20 1/4	22 - 24 1/4	2 1/2	10
24 x 24	22 - 24 1/4	22 - 24 1/4	2 1/2	10