Postage Saving ClearClasp® envelopes, with reusable Redi-Tac closure for repeated use when using for storage or routing. This innovative technology eliminates the USPS upcharge to mail a metal clasp. Fully gummed flap provides a secure permanent seal when mailing. 28-lb brown Kraft stock is sturdy to protect contents while in transit or storage. Seam Type: Center; Flap Type: Cheese Blade; Trade Size: #90; Security Tinted: No.