The rule that changed my mind about Dietzgen rules. Previously, I'd only seen fairly beat-up Mannheim rules and plastic 6" rules like the 1771. This one, though, is at least as nice as the K&E competition, and is even nicer in some ways: the bit where the slide goes has a nice plastic coating (evidently this is what Dietzgen means by "Microglide". I can't say that name without giggling, though) and the endpieces on the cursor are stylish black (it goes with every color, you know). Plus, this is a vector-type rule, with the hyperbolic functions that my version of the K&E doesn't have.