These stamps are a convenient way for customers to pay for Priority Mail and Priority Mail Express Flat Rate shipping with a single stamp. Priority Mail is a fast domestic service that includes flat rate shipping in one, two or three business days based on where your package starts and where it’s being sent. Priority Mail Express is the fastest domestic service, with limited exceptions; available 365 days a year, with a money-back guarantee and delivery shipping to most U.S. addresses, including PO Boxes.

Note: These are not forever stamps, you will need to check with post office to see if addition regular stamps needed to match current face value