The stamps for your letters
Memento
Cancelled First-day cover «100 years Swiss Air Navigation»
Single stamp (1 stamp, postage value CHF 2.10) on first-day cover (FDC) C6
CHF 3.00 Cancelled First-day cover «100 years Swiss Air Navigation»
Miniature sheet (10 stamps, postage value CHF 21.00) on first-day cover (FDC) C5
CHF 22.20