duct size overall dims
2.25 by 10 inches 2.875 by 11.375
2.25 by 14 inches 2.875 by 15.375
4 by 10 inches 5.75 by 11.75
4 by 12 inches 5.875 by 13.875
4 by 14 inches 6 by 16
4 by 8 inches 5.875 by 9.75
6 by 10 inches 7.875 by 11.875
6 by 12 inches 7.875 by 13.875
6 by 14 inches 8 by 15.875
6 by 6 inches 7.25 by 7.25
8 by 12 inches 10 by 13.875
8 by 14 inches 10 by 16.125
8 by 8 inches 9 by 9
10 by 10 inches 11.25 by 11.25
10 by 14 inches 11.875 by 16
12 by 12 inches 13.75 by 13.75
14 by 14 inches 15.875 by 15.875
14 by 24 inches 15.75 by 25.875
14 by 30 inches 16.25 by 31.875
20 by 30 inches 22 by 31.75