The OEM Smead Poly Envelope is designed to protect important documents long-term with its acid-free, archival quality material. Made from heavy-duty, PVC-free polypropylene, these envelopes resist tears and repel moisture. The tough, side-loading design features 1-1/4 expanding gussets, providing ample space to hold more than 200 sheets of paper. Each letter-size envelope includes a hook-and-loop closure for easy opening and closing.