Special commission for German lighting company OSRAM for calculating for calculating lifespan of filament lightbulbs + Table of values on back - see also later & wider version  

Specially commissioned & extra wide by now defunct German Textile company Sartorius Werke AG + nomogram & conversion table on back

Specially commissioned by multinational Philips for film projection in cinemas + many film-related gauge marks 

Specially commissioned slide chart by Dutch Office Supplier Ahrend for selecting fit-for-purpose wire rope with fibre core but based on a Shell (BPM) copyrighted design (MESC 1958)   

Special commission for defunct German textile company F.C. Bayerlein + many conversion style gauge marks

 Specially commissioned ruler by Finnish stationers Ab Herman Lindell Oy - for measuring distances/areas - cursor extension suggests results were transposed for further working - name Herman Lindell + “import” & “copyrighted” in Finnish on the back

Specially commissioned slide chart for German subsidiary of Shell Chemicals for general rubber characteristics on front but specifically for Cariflex brand of isoprene rubber (IR), butadiene rubber (BR) & styrene butadiene rubber (SBR) on back + E suffix to model no. suggests versions made in other languages    

Specially commissioned by German refinery & chain of garages Erdölwerke Frisia AG for crude oil related calculations + many crude oil related gauge marks & formulas/extra information on back- 

Specially commissioned hybrid slide rule/slide chart by now defunct tool maker Smith International Deutschland GmbH 

Specially commissioned for German photographic suppliers Hoh & Hahne -  HOHLUX was one of their band names.

Specially commissioned by Bundesamt für Wehrtechnik und Beschaffung (BWB) as modern day mit Strichteilung version (inner scales calibrated in 6400 milliradians or MILS) of High Altitude Calculator for German Armed forces (NATO NSN No.: 6660-12-140-6737) for global missile trajectories or possibly jet stream & its effect on missiles/planes flying at high altitude

Special commission for oil major ESSO - 2 nomograms for heating oil & D&P/Aristo co-branding on back

Special commission & registered design for German steel foundry Stahlwerke Bochum & Lichtenberg for calculating weight of steel bars, sheets & strips + Table of factors on back of envelope

Specially commissioned by BP Germany for calculating supply requirements of household heating/fuel oil - K Factor is a way of showing (litres/degree day) how fast a consumer uses heating oil (analogy = fuel consumption of a car) 

Specially commissioned by oil major BP for calculating stack-loss efficiency in a heating system running on heating oil. 

Specially commissioned slide chart by German lighting company OSRAM for gas-filled (front) & vacuum-filled (back) lightbulbs 

Specially commissioned by German maker of electrical equipment AEG  based on model 89 body but with top & bottom scales on front face replaced by a two-part Cos-Phi power factor scale + AEG Vibrationstechnik & cursor window + 1 hairline in back

Specially commissioned by Karl-Heinz Poser apparently for lens adjustment in ophthalmology

Specially commissioned by a German Dr. Reiner for calculating correction needed for patients suffering from presbyopia (inability to focus on nearby objects) + table on back 

Special commission for German lighting company OSRAM for calculating for calculating lifespan of filament lightbulbs + Table of SCE values on back - see also earlier & narrower version 

Specially commissioned by now defunct German maker of machines for tobacco industry Hauni Maschinenbau for dry & water retained calculations with raw tobacco & cigarettes  

Special commission for German steel foundry BAU-STAHLGEWERBE for calculating sizes of various steel products  

Specially commissioned by Swiss company Rieter suppling machines/systems for making yarn + specialist scale in well of stock + cm scale & Table of constants on back 

Specialist model for aerial photography