ViewFront Poly Booklet Envelope, Side Opening, 11 x 9 1/2, 3 Colors, 4/Pack, Sold as 1 Package, 4 Each per Package Transparent, colored polypropylene expandable envelope with a horizontal, file-style orientation and a string and button closure. Moisture-resistant polypropylene. Horizontal, file-style orientation. Full-sized back pocket. Elastic string and riveted button closure.