What are the "rough opening" requirements for the aluminum frame fantom series deer blind deerstand windows?

The standard recommended "cutouts" or rough opening sizes are as follows:
For the 12 x 48 Size; R/O Size: cut out 13 3/8" X 49 1/2"
For the 12 x 36 Size: R/O Size: cut out 13 3/8" X 37 1/4"
For the 12 x 30 Size: R/O Cut Out 13 3/8" X 31 1/4"
For the 12 x 18 Size: R/O Cut out 13 3/8" X 19/1/4"
For the 12 x 16 Size: R/O cut out 13 1/4" X 16/1/4"