Are these on cover ? Or on piece?
Very nice example of a 'Seige' postmark and highly collectable.
As Wadmalatz said, these were first issued on April 25th and these look like a late usage.
Issued in tete-Beche sheetlets of 8, 2x4 with a colour bar seperating the two blocks.
Inscriptions in both English and Hebrew were at the top of the sheet.
This is really lovely....drool material.
Seige Postmark :
This cover went by Sea because the Western Galillee was cut off due to the War [of Independence]