|This United States Postal Service approved, reusable transit sack is perfect for expediting paperwork by mail or messenger. Ideal for intra-company communications as well as company to company deliveries. Contents are kept confidential by looping self-locking security seal (sold separately) through grommet and zipper pull. Durable vinyl construction with reinforced seams so it stands up to everyday use. Water-resistant so even valuable documents are protected. Framed window holder for identification purposes.