OEM Quality Park Survivor First Class Envelopes are designed for secure and reliable mailing. These envelopes feature a patented release strip for easy opening and a convenient Flap-Stik closure that does not require moisture to seal. Made from DuPont Tyvek, they are much stronger and more secure than traditional paper envelopes, ensuring they won't rip, tear, or puncture. Lightweight and water-resistant, these envelopes help save on postage costs while providing a dependable solution for your mailing needs.