Survivor 12 x 16 x 2 Tyvek Expansion Catalog Mailers with Self Seal Closure, 14 lb, Puncture, Tear and Moisture Resistant DuPont Tyvek Envelopes, 25 per Box (R4292) Flap-Stik SELF SEAL REMOVABLE STRIP: provides a clean, quick seal immediately upon contact. Simply peel off the adhesive strip to create a full, secure seal that won't open or tear. The self-seal peel-off strip protects the adhesive from dust for a longer shelf life. The releasestrip FEATURE of the Survivor Tyvek envelope make the contents easily accessible to the recipient, yet maintains the security of the envelopes contents. MULTIPLE USES: DuPont Tyvek provides superior toughness and durability compared to heavy kraft paper and even other high-strength materials used for envelopes and packaging. It resists rips, punctures and moisture, providing much more protection for the contents of your envelope. POSTAGE SAVING OPPORTUNITIES: Tyvek is also lightweight and can save on postage as well. Major overnight shippers and the United States Postal Service choose envelopes made of Tyvek for priority packaging because it protects important things, ensuring that they arrive in good condition. 25 ENVELOPES IN EACH BOX: provides a great value to ensure that you have enough for all your personal and professional correspondence.