Those wacky germans, they know their plastics. This is a really nice log-log rule, in spite of being all-plastic (with the exception of the cursor endpieces, which seem to be brass or something). It's rules like this that make things like the Sterling rules look so cheesy. Note the nifty feet on the back of the rule so's you can use it while it's sitting on your desk. I actually accidentally got the manual for this rule in the box with a Pickett I bought. You care. You care a lot.
This rule is also marked 'Charvoz', and there's a Charvoz logo above the Aristo logo on the flap of the case. There was an article in the Journal of the Oughtred Society about Aristo, but i don't remember it mentioning Charvoz. It just goes to show you, ummmm, something, i'm sure.