OEM Quality Park First Class Expansion Envelopes, sold in a carton of 100. Made from heavyweight Tyvek, these envelopes provide superior protection for mailing bulky items. The open-end style and Flap-Stik closure ensure convenient use, while the DuPont Tyvek material is designed to resist ripping, tearing, or puncturing for enhanced security. Additionally, the water-resistant and moisture-resistant properties make these envelopes suitable for harsh mailing conditions.