OEM Quality Park Survivor Tyvek plain envelopes, sold in a box of 50. These open-end catalog 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 resistant to ripping, tearing, and puncturing, making them more secure than traditional paper envelopes. Additionally, they are lightweight and water-resistant, helping to save on postage costs.