JAM PAPER Tyvek Tear-Proof Open End Catalog Envelopes - 11 1/2 x 14 1/2 - Black - 25/Pack Color: Black Size: 11 1/2 x 14 1/2 inches Quantity: 25 Envelopes/pack Tyvek is a registered trademark of DuPont, the established company responsible for developing this durable polymer. It is composed of high-density polyethylene fibers, a synthetic material that is extremely hard to rip and tear. Perfect for any document you need serious protection for.