Save the Post Office on X: "#OTD #OTDPostal Nov. 20, 2004, The Priority Mail Flat Rate Box is introduced, as part of a 2-year experiment. The boxes themselves are free but may
Pre-Paid – C5 Window – Whitestone Post
Priority Mail Large Flat Rate Box 12 1/4" x 12 1/4" x 6" – Stamps.com Supplies Store
Priority Mail Express Box 15 5/8" x 12 7/16" x 3 1/8" – Stamps.com Supplies Store
Priority Mail | USPS
Sharps 3 Gallon Container Mail Back PrePaid Postage FREE Disposal SHIPS FAST | eBay