Priority Mail Flat-Rate Envelope
Envelope size: 9-1/2 X 12-1/2 inches.
One low price for any mailable item sent in a flat-rate envelope provided by the Postal Service, regardless of weight or U.S. destination.You can print Priority Mail labels with postage with Click-N-Ship at USPS.com and receive a price reduction.
When sealing a flat-rate envelope, the container flaps must be able to close within the normal folds. Tape may be applied to the flaps and seams to reinforce the container; provided the design of the container is not enlarged by opening the sides and the container is not reconstructed in any way.
