This is a British Solomon Islands OHMS, or ON HIS/HER MAJESTY'S SERVICE Registered Cover.  This one was sent from Honiara to Arnhem, Holland on 8/18/1950.

What makes this little beauty really special is the DOUBLE OVAL PROTECTORATE POSTMASTER, HONIARA on the lower left.  This is RARE.  However, it also has a Honiara CDS on the front and back, a GPO BY AIR on the back and an ARNHEM RECEIVER in BLUE.  Lastly, but not least, it has the VERY RARE DOUBLE BOXED BRITISH SOLOMAN ISLANDS, HONIARA, CROWN POSTAGE PAID marking in VIOLET on the front.  See RL Volume 4, Page 537 for more information.

This item is over $100 USD so I will ship it using Priority Mail in the US, and Registered Mail overseas.  This is to ensure that it reaches you in a safe and timely manner!