Sans & Streiffe are believed to have been based near Chicago, Illinois and were suppliers of "instruments" such as slide rules, drawing equipment, telescopes, binoculars, etc. Like many similar companies they did not actually manufacture most of their inventory but had it manufactured with their label.

In the case of Sans & Streiffe they seemed to have had their rules made by Relay/Ricoh.

No trace of the company appears after some time in the 1960s and they appear to have gone out of business around then. Many other engineering supply companies were amalgamated or went out of business around the same time.

My thanks to Martin Eble for this update.