This genuinely flown cover is one of 192 that was flown on the First Flight Prague to Užhorod on 3 June 1935, 7th hour. The flight then continued with the rest of the mail to Kluž and Bucharest. It bears the special commemorative cancel for this flight over a Type I, 2 Kč airmail stamp from the 16 December 1930 definitive set (Type I has a small break in the inner frame line in the lower left corner, and is a longer but narrower rectangular stamp then the Type II). It is perforated 13 3/4 and is a right margin copy showing the vertical 8-line stress bar imprint (making the stamp valued at 10% more).
The franking is correct — 1 Kč for a letter up to 20 gm going a greater distance within the country, and a 1 Kč surcharge for an airmail letter up to 20 gm.
You will note that the address is a little skimpy, having no street address or house number.
On the reverse is another special commemorative cancel for its arrival in Užhorod showing a date of 3 June 1935, 13th hour. Across the back is a hand-stamp saying “VYVOLÁNO LISTONOSEM NEZNÁMÝ” which loosely translates into “announced by postman as unknown”, with initials, and then a return PRAHA 36 cancel dated 5 June 1935.
I do not know the purpose of the “6945”.
A nice clean cover.