Media rate is tricky. Some clerks will let it go thru and others won't. Just had that happen to me a few days ago. When the clerk asked me what was in there I said a book then she said what kind of book so I said a quilt book, and she said it can't be sent media so I sent it USPS Flat Rate Envelope. A few weeks ago, the clerk asked me what was in there and I said some books and it went thru. And the post office can open it if they feel it is not the correct media being sent. Any of the USPS Flat Rates are best, parcel post or first class mail, whichever is cheaper. Good luck!