170 years of Brazilian stamps ox eyes - block mint never hinged, Brazil

For the international stamp exhibition BRASILIANA 2013 in Rio de Janeiro, the postal administration of Brazil issued a pad for the anniversary "170 years of Brazilian stamps ox eyes". The three stamps in the block reproduce the first three Brazilian postage stamps "Large value figure in a lying oval" (so-called ox eyes) from August 1, 1843.
"Ox eyes" are a term from the collector's language for Brazil's first postage stamps. After Great Britain and the Zurich Cantonal Post Office, Brazil was the third country in the world to issue stick-on postage stamps. This made it the first country outside of Europe.