Nestler 23E Rietz Ivoride Celluloid mahogany slide rule in case 1930 Germany

This highly unusual slide rule version of 23 Rietz model was made only for a few year in the 1930’s between 1931 and 1934. The material used is called Ivoride which mimics Ivory, hence the yellow colour. There is a in-depth description of this unusual material here at rechenschieber.org (celluloid-bei-nestler). It comes in the original signed container (tape on both sides). Rule is great condition, no cracks or chips but there are formulas needles scratched in. There is a small crack in the glass of the cursor. It measures 28,5 cm or 11.5 inches in length. Check the attached video on how to work your vintage man tool : slide rule operation instructions!