Mint = With original gum. Unused = Stamp without any gum or regummed. We review all best offers. Certain items, such as zeppelins and high denom notes, have very little profit margins leaving very little room for discounting. Offers within 5% of the asking price have the best chance of acceptance.Stamps described with faults are NOT returnable. Stamps generic certificates from William Weiss, PSE, APS, or the Philatelic Foundation are accepted. NOTE "graded" certificates or "encased" items are not accepted. Proof of the inability of a competent authority to express an opinion is not grounds for return. The item "#568 & C11 ON FIRST ZEPPELIN FLIGHT COVER USA TO GERMANY OCT 28,1928 BT5813" is in sale since Sunday, January 22, 2017. This item is in the category "Stamps\United States\Covers\Event Covers\First Flight". The seller is "billsbargainstamps" and is located in New Milford, New Jersey. This item can be shipped worldwide.