These Survivor® envelopes expand to provide lightweight, inexpensive shipping for bulky items. Expandable envelopes are made of puncture, tear and moisture-resistant DuPont™ Tyvek® material. Envelopes made with Tyvek® are half the weight of heavy duty paper envelopes, so you save on postage with each mailing. Our tough expandable mailers resist overstuffing, bad weather and rough handling to deliver your contents intact. With easy to use Quality Park® Redi-Strip® envelope closures, just peel and press for an instant seal. Redi-Strip® envelopes are the perfect mailroom update for concerns about surface germs in the workplace. Skip the yuck, stay safe and save time with every mailing. Plus, peelable paper strips protect your adhesive from dust so envelopes last longer in storage. The large envelope makes a versatile mailer for all kinds of thick enclosures, from paper to textiles. Opens wide to accommodate binders, books, manuscripts, transcripts and more. Tyvek® is a trademark of DuPont used under license by LSC Communications US, LLC d/b/a TOPS Products.