When looking for an envelope that offers the ultimate in durability, then there is no looking past Tyvek open end catalog envelopes. These envelopes are made from special 14lb white spun bonded Olefin that’s tear and moisture resistant. These envelopes also come with the branded Kwik-Tak sealing system. When sealing the envelope customers need to peel off the tape liner, close the flap and apply pressure. Thanks to their superior durability, these 6 X 9 - 14 Tyvek open end catalog Kwik-Tak envelopes are ideally suited for sending heavy stacks of documents. These are also the envelope of choice when mailing to international destinations.