Of course true! Been trying to understand condom sizes better, have to say not that easy - calculations, conversions, the advertised dimensions are "flat measurements" not straightforward ones, wow!
I think I am getting the general idea more or less, but you would think that for something that is the primary item for safety there would be something much easier and accessible!
No matter what like so many other things, no real way to be sure in advance until actually trying.