Issue of 1867 Handstamped in Black.
 

TYPE I HANDSTAMPED

1878 SAN SALVADOR  to PARIS, FRANCE
Postmarked April 24. Registered and rated 24 Reales.
Franked with 4 Reales Type I "CONTRA SELLO"  (strip of 3, a pair and a single).
Via PANAMA, May 6. Charged 17/8d at British Consular Office, paid using GB adhesives
tied with "C65" barrel killers. Received LONDON, May 26 and PARIS, May 29.

THE LARGEST RECORDED USAGE OF 4 REALES "CONTRA SELLO" ISSUE

THE ONLY RECORDED REGISTERED COVER FOR THE ISSUE

THE ONLY RECORDED DOUBLE HANDSTAMPED ERROR ON COVER (Position 6)