This one's somewhat similar to the Concise model 28, mostly in that it's a simple circular rule with a rotating inner disk, a fixed outer disk, and a simple cursor. It's got more scales than that one, though, it's metal (probably steel, though i'm not positive), and it was made in Hungary. Kendra spotted this at a flea market, in a booth i'd already looked in. I almost think i'm getting afraid of buying slide rules at flea markets because of the look you get when you act like you actually want to buy the thing. The folks who sold me this one looked at me like i was from mars, i swear. I don't really know if 'Rotor' is a model or a manufacturer. The logo on the back of the rule is probably the manufacturer, but i sure can't tell what it says. One interesting thing about this rule is that the outer edge is serrated. i'm not sure what that was supposed to accomplish, unless the rule could double as a blade for a very small circular saw.