Stampless official cover with embossed 'DE OFICIO DE SAN SALVADOR' Star cachet at top with fine strike of the circular 'Bar' type handstamp in blue inscribed 'CORREOS DE EL SALVADOR DE OFICIO' which was used as a handstamp on the 1896 'Seebeck' official issue with OFICINA DE CORREOS SAN SALVADOR cds in blue dated OCT 11 1898 also on front with '2' in blue crayon alongside. Addressed to COSTA RICA. Cover has some light overall toning, and is a little roughly opened at right but a very rare use of this handstamp in the correct period of use and a proving piece for the genuine handstamp.