When I checked with the USPS website the max size for first class mail is 6 1/8" on the short side and this mailer is 7" not 6" as per the product description. To use it I had to fold and tape down the top and bottom edges to make it fit within the USPS requirements for first class mail otherwise it would have to go as a package at significantly higher cost.
We have purchased these repeatedly and have been very happy with the performance. We use them for mailing purposes and are pleased with the quality and strength of the product. We will continue to purchase this product.