Tyvek® FLAT ENVELOPES Open End, Zip Stick - Plain 500/Carton, Flaps Folded Tyvek SUB 11Bulk Tyvek envelopes come with easy to use self seal closure. No licking and sticking needed. The seal flap works without moisture. Tyvek envelopes are at least 10 times stronger than standard paper envelopes which means you can put alot more contents in each one. Furthermore, they weigh half as much which can reduce postage costs. eCRATER sellers like this item for their more bulky items.Answers to often asked questions about Tyvek Catalog Envelopes SUB 11:The term "SUB 11" refers to the weight of the substrate. Tyvek comes in 11 #, 14 #, and 18#. We carry all three..see our store > "Catalog" designates the opening to be on the short dimension of the envelope. "Booklet" designates opening on the long dimension.All of our products are made in the United States of AmericaBulk Tyvek Envelope SpecificationsSize: 6 1/2 X 9 1/2Packaged: 500 per cartonClosure: Zip Stick self seal flapWeight: 11 lbStock #: 1195PLAdditionalService: Custom printing up to 4 colors. Ask for details.Discount: Multiple Carton Discounts.Not sure? Ask for a free 6 1/2 X 9 1/2 Tyvek Envelope sample today.Need a different size or style? Check out my other items!