The ruler is more for cutting pieces for on-point blocks so that the finished block is an even size. It's not for setting whole quilts on point. For those, you still do the math, but the math can come from a more easily measurable number because your blocks are an even size. The even size is important, because say, you want to mix a block with on-point elements with other 12" block that perhaps don't have on-point elements. If you want the finished size of the on-point block to be 12", you absolutely have to use templates -- or this ruler. If you use Math, the result is that either the on-point elements won't have an even measurement or the non-on-point elements won't have an even measurement so your resulting blocks won't be 12". It's a drafting tool, really. The Generations Quilt site has more detail, but it looks like my link to it was taken away. Maybe when I get the tool, I'll post a tutorial.
Anyway, I was wondering if anyone had made use of it, but maybe no? PaperPrincess, you're still on for the challenge. ;-).
Yeah, I wrote Amazon about the description error, beads? but no response. I ended up ordering the ruler from another site. It's not here yet!