Transparent, moisture resistant polypropylene envelope keeps materials neat and clean. Horizontal, file-style orientation makes inserting and removing documents easy. Full-sized, open-top back pocket provides convenient quick-access storage space. Durable elastic string and riveted button closure is designed for heavy use. Envelope Size: 11 x 9 1/2; Global Product Type: Envelopes/Mailers; Envelope/Mailer Type: Expanding Pocket; Closure: String and Button.