OEM Quality Park Plain Expansion Envelopes provide superior protection for mailing bulky items that are not too heavy. These envelopes are an ideal alternative to costly boxes or cartons, featuring an open-end style and a convenient Flap-Stik closure. Made from DuPont Tyvek, these envelopes are designed to resist ripping, tearing, and puncturing, offering much greater strength and security than traditional paper envelopes. They are also water-resistant and moisture-resistant, ensuring your items remain protected during transit.