PolyZip Envelope features a zip closure that quickly and easily slides open and closed. Ideal for carrying supplies and organizing projects. The unique PolyZip design protects your materials from the elements, forming a dust-resistant, water-resistant seal unmatched by traditional paper and poly envelopes. The clear front pocket offers a separate area to secure a cover sheet or routing slip. Gusset expands 1-1/4" for added storage. Durable, polypropylene envelope is acid-free and archival-safe for long-term storage.