What is the cut out size for the 14 in. x 6 in. Bonderized Steel Vulcan Foundation Vent?

For the 6 x 14, the rough opening is 13-1/2 x 5-1/2. For the 8 x 14, the rough opening is 13-1/2 x 7-1/2.

For the 6 x 14, the rough opening is 13-1/2 x 5-1/2. For the 8 x 14, the rough opening is 13-1/2 x 7-1/2..