OEM Quality Park Plain Expansion Envelopes are designed for mailing bulky items with ease. These regular-weight envelopes provide superior protection and are an ideal alternative to costly boxes or cartons. Made from durable DuPont Tyvek, they resist ripping, tearing, and puncturing, ensuring your items are secure during transit. The envelopes feature an open-end style with a convenient Flap-Stik closure, making them easy to use. They are also water-resistant and moisture-resistant, offering added reliability for your mailing needs.