So a couple weeks ago I picked up a couple Shapton stones. When I bought them, they were advertised as the Shapton Glass stones... turns out they're the Pro stones instead. What is the real difference in them, other than obviously one is mounted on glass and the other isn't. I'm a bit compulsive on making my stuff match (unless I can find a good reason not to) so I'm trying to do the research to decide if there is a good reason to go with one over the other. I've never set eyes on a Shapton Glass, but they look to be thinner than the Pro. Is this the case?