This is a Cayman Islands Postage Due Cover.  It was sent to Ernest Panton, the Cayman Postmaster, from Kingston Jamaica on 6/13/1933.

This cover has some interesting things on it.  For starters, it has THE JAMAICA DUE HANDSTAMP in BLACK.  It also has the Cayman 2d stamp used for postage due on 6/30/1933.

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