The United States Postal Service uses the words "flats" and "nonletters" interchangeably to refer to large envelopes, newsletters, and magazines.
To fit the definition a flat must: Furthermore, the item must be somewhat bendable: see the USPS Domestic Mail Manual for exact details.
This general rule does not apply to: Automation rate flats and Standard Mail Enhanced Carrier Route flats.
The maximum size for a flat provides enough room to enclose much material.
This United States government–related article is a stub.