Package contains: 25 pack 13 x 18 inch Rigid Mailers with "DO NOT BEND" labels. Material?paperboard Size: 13 x 18 inch The adhesive on cardboard Rigid Mailers creates a strong lasting seal and prevents your contents from falling out during transit and protect them well. These Photo Document Envelopes are perfect for mailing soft goods, photographs, documents and printouts. Ideal choice post offices, logistic shipping companies, packaging wholesalers, mail order companies, office stationery suppliers, online stores, home or personal use.