Catalog envelopes with Redi-Strip® closure for home or office mailing, storage and organizing. Keeping your home or business organized is imperative! Whatever your needs, catalog envelopes are a must for keeping projects, files and mailings manageable. These heavyweight catalog envelopes are made of 28-lb stock that can withstand extensive handling, as well as mailing. USPS First Class Mail. Seam Type: Center; Flap Type: Cheese Blade; Trade Size: #10 1/2; Security Tinted: No.