In some cases, it is obvious that the cover is philatelic. In others, it's not so obvious. These four all seem to be philatelic. Use of the 1/2 centavo and 2 1/2 centavos stamps on non-philatelic covers are almost impossible: for the 1/2 centavo, it fulfilled printed matter rates, and the 2 1/2 centavos stamp was supposed to be used on Braille mail (for the blind), for which use I have not seen a cover, and I have been collecting this series since the early 1990s.
The first cover is to Chile.
A covet to Belgium.
Another cover to Belgium, this one to a stamp dealer.
A cover to the United States. Curious posting of the stamps upside down.
