Inside/Outside Diameter (for printing)

Sorry for the stupid post, but tried search and found nothing.

Re: Printing Labels

I know that the outer is 120mm and the inner is 43mm for printable blanks. Then what is the inner size when there is no stack ring?

I have the Prodisc 8X DVD-R Printable surface blanks. I am using the Epson R200 to print, and there is nothing that suggest what the inside diameter is without stack ring, only has a custom setting.