Quality Park 10 x 13 First Class Catalog Envelopes have a green diamond border that gets your package noticed. Mailers have Redi-Strip self-sealing closures for a fast, instant seal—just peel and press. Made of 28 lb white wove stock that can withstand extensive handling through the mail. 100 Per box.10" x 13" First Class Envelopes. Self sealing. 28 lb White wove paper. 100 Per box.FIRST CLASS MAILERS: 10 x13 envelopes have green diamond borders to make you mail stand out from the crowd.VERSATILE SIZE: 10" x13" envelopes fits 8-1/2" x 11" letters or larger documents, catalogs or photos flat, not folded.FASTER WAY TO FOLD, STUFF & SEAL: Your time is too valuable to spend licking envelopes. Redi-Strip self-sealing catalog envelopes work without moisture—just peel to seal.LONGER LASTING IN STORAGE: Peelable paper strip protects your adhesive from dust so envelopes last longer on the shelf.ELMINATE YUCK FOR LESS: Goodbye drippy moistener sponges! Self-sealing envelopes offer affordable alternatives to standard envelopes.