You may order free packaging supplies at /store. Weight restrictions for Priority Mail International Large and Medium Flat Rate Boxes are 20 pounds, and 4 pounds for Priority Mail International Flat Rate Envelopes and Small Flat Rate Priced Boxes. Weight restrictions for Priority Mail Express International Flat Rate Envelopes are 4 pounds. The small flat rate box and padded flat rate envelope are what hurts me the most.
Weight restrictions for domestic Priority Mail Express Flat Rate Envelopes, and Priority Mail Flat Rate Envelopes and Boxes are 70 pounds. 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. When sealing a Flat Rate Box or Flat Rate Envelope, the container flaps must be able to close within the normal folds.
Note: Flat Rate prices are available when material is sent in a USPS -produced Flat Rate Envelope or Box.