Versatile envelopes simplify your mailing and storage needs Ideal for sending flat, bulky materials like catalogs and documents. Flap is located on the short side to help prevent items from falling out. Made of 70-lb paper. Moisture-activated glue closure seals contents for secure mailing. LUX Open-End Envelopes, 10in. x 13in., Avocado Green, Pack Of 1,000 is one of many Open End & Catalog Envelopes available through Office Depot. Made by LUX.