A word or two about our 1st Day Covers - We primarily use the Collectibles eBay category for them and we treat them accordingly. All materials used, including the mat, are acid free. They are stuffed with card stock to prevent the glue-line from bleeding through over time.The entire cover is shown, including the cachet (artwork on the envelope) - we want to show that the cover is an actual envelope. We use clear corner mounts so that the cover may be removed and retains its good to mint condition. We choose our covers not only for their condition, but for the beauty of their cachets - all 1st Day Covers are cacheted. Commemorative Covers are mounted and stuffed the same way. You can rest assured that you are getting the best available and we back it up with a Certificate of Authenticity for 1st Day Covers.