Large registered cover fr. with 2dr/40l. violet in bl.4 and 20l./25l. light blue perf 11 1/2 with surcharge inverted, canc "ΑΘΗΝΑΙ-6*17.ΝΟΕΜ.1700", arr. ΠΕΙΡΑΙΕΥΣ*18.ΝΟΕΜ.1900". Five wax seals on reverse. Cover folded in middle. Extremly rare. (Hellas 138+139b).