United States. (Netherlands Air Force). 1945. Air Mail postal stationery envelope 'six cents' orange (written from "Res 1st Lt. Charles Lalieu, Royal Netherlands Air Force) upgraded with 'Transporter' SG A901, 6c carmine (3) and SG 910, 5c violet tied by 'U.S. Army Postal Service/ A.P.O.' date stamp addressed to Holland with hand-struck 'Insufficiently Prepaid For/ Trans-Atlantic Air Mail Service' in carmine on face with instructional 'Return For Postage (Air Mail 30c per 1/2 oz 1c more), on reverse Antwerp transit. Very fine.