Cuba 1958 - Sc 594, C181 - (EDIFIL 744-45) for the regularly issued stamps.
Wright Banknote Company imperforate plate proof blocks of 4 of the 1958 Jose Miguel Gomez issue, with full original gum and never hinged. The 4c value is printed in a lighter hue of blue than the issued stamp. Very, very scarce. Not listed in EDIFIL or any other catalogues we know of. Only 100 stamps believed to exist and only few available to collectors at this time since a complete set of sheets of 50 remains uncut.