Quick One: 40B Glass Size

[SkinnyPete]

Need to cut glass baffles for a 40 gallon breeder tank "36x18x16". I don't have the tank yet and my wife is asking if she can buy both the tank and have the glass for baffles cut for me as an xmas gift. So, I'd need to give her exact measurements. Anyone know what the inner dimensions are? I'm thinking of going 11" for height, but not sure what the length should be. Some sites say outer dimension is 18 1/4" wide, some say 18". I was going to email all-glass to inquire but thought someone might know here first.

Thanks all.

- Skins