Steinheil Antiplanet Lens patented in Germany (patent Nr. D.R.P. 16354), England and USA.
By multiplying Steinheil Lin 2.3x times, you get an approximate opening in mm (e.g Steinheil 7 Lin x2.3 you get an opening of approx 16-17mm). There is no way to calculate focal length or coverage of the lens by dividing or multiplying “lines”. This needs to be checked from the catalog.