O47//56 POST OFFICE DEPT OFFICIALS MH AND USED CAT. WAIT FOR AN INVOICE AND DO NOT PAY TILL WE HAVE DETERMINED THE COURSE OF ACTION. BE SURE TO LOOK IN MY STORE.MAKE ME AN OFFER, THE WORST I CAN SAY IS NO. Communication is a very valuable tool. Unfortunately, about half of those buyers never bothered to return the courtesy once the items were received. I will now leave feedback for any and all once it has been received. Please accept my apologies, but I find more and more sellers needing to follow this course of action. O47//56 POST OFFICE DEPT OFFICIALS MH AND USED CAT. $520.00 PG6" is in sale since Friday, April 21, 2017. This item is in the category "Stamps\United States\Back of Book\Other US Back of Book Stamps". The seller is "redgsr" and is located in Vienna, Virginia. This item can be shipped worldwide.