Attractive and specialized collection of Swiss airmail stamps (Flugpost) from the years 1923–1941, showing a broad range of paper varieties and printings. The lot includes numerous classic airmail issues with different denominations and designs. Several stamps are shown with both front and reverse, clearly illustrating differences in paper, gum and production characteristics. The collection is neatly organized and annotated with SBK (Zumstein) catalogue numbers. Condition: Mostly used, as issued. Overall fine to very fine for the period. Some stamps show light hinge marks, minor gum disturbance, paper toning or traces of mounting on the reverse, all consistent with age. No major defects observed. Catalogue value: approx. 885 CHF (according to SBK / Zumstein, as noted). A solid and well-assembled lot, ideal for collectors interested in Swiss airmail issues and paper varieties.