Nestler full set magnifier manual Rietz Darmstadt slide rules in case 1930 Germany

Interesting set of 2 early slide rules by Nestler from Germany from around 1930. There is a Nestler 21 system Darmstadt and a Nestler 23R, system Rietz both in their original signed containers. In addition there is an original Nestler booklet which covers both systems. On top of that there is a special magnifying cursor instead of the normal cursor. Both cursors work on both slide rules. This magnifier was a rare and expensive accessory. The fact that this booklet survived all these years is exceptional as well, the text is in German. There are signs of use and age but everything is complete and working, no cracks or chips. The slide rulesmeasures ca. 29 cm or 11 3/4 inches long. Check the attached video on how to work your vintage man tool : slide rule operation instructions!