100 year old 125mm slide rule

I bought this slide rule (described by the seller as an old ruler) for €15 on eBay. It seems that Klawun branded them for training students - not quite sure who the original manufacturer was. It's almost 100 years old and in perfect condition. I'm very happy with the find.

Now that I've photographed it, I've put it back on eBay, in the spirit of catch and release.

More pics:

https://commons.wikimedia.org/wiki/File:Slide_rule_J_Klawun_Hannover_08.jpg https://commons.wikimedia.org/wiki/File:Slide_rule_J_Klawun_Hannover_05.jpg https://commons.wikimedia.org/wiki/File:Slide_rule_J_Klawun_Hannover_04.jpg https://commons.wikimedia.org/wiki/File:Slide_rule_J_Klawun_Hannover_in_box.jpg https://commons.wikimedia.org/wiki/File:Slide_rule_J_Klawun_Hannover_03.jpg https://commons.wikimedia.org/wiki/File:Slide_rule_J_Klawun_Hannover_box.jpg