Nestler 40a Kaufmann 55 cm 22″ commercial slide rule 1940 Germany

This is a beautiful large slide rule used for dealers and traders of their time that needed to do financial calculations and deal with exchange rates for various currencies. Hence the name “Kaufmann” which is German for Dealer. I am sure this long slide rule added to the standing of the handler. In addition it would be more accurate then the standard model 40. I am guesstimating this one is from ca. 1940. Everything is complete, no cracks, chips or dings and in working condition and perfect very large glass cursor. There are some signs of age and from normal use. There are clear marks from storage and some tape  on the corners of the complete and original cardboard container. It measures about 55 cm or 22 inches wide. Check the attached video on how to work your vintage man tool : slide rule operation instructions!