Aristo 80151 BG Concrete pocket slide rule case 1960 Germany

This special pocket slide rule comes in the original unmarked leather sleeve, with manual and is made by Aristo from Germany. This model is the pocket BG  version, there is also the normal size 90184 BG. It is a special slide rule made for the Company Baustahlgewebe from Düsseldorf Germany. This slide rule is specifically made for calculating concrete steel mats for use in construction. It has extra scales on top and bottom. The full manual explains the way to use them, but they also point toward contacting g the firm for choice of materials, so this seems to be a specific made advertising aid only made in small quantities for this specific firm. Curser and rule are complete there are only small signs of use on the slide rule and cursor. It measures 16 cm or 6 1/4 inches. Do check the attached video on how to work your vintage man tool : slide rule operation instructions!