To save on postage, clasp envelopes feature Resealable Redi-Tac technology on the closure to replace the traditional metal clasp for better repeated use and durability. ClearClasp envelopes save money in postage by eliminating the additional USPS handling charges that are required for metal clasp envelopes. 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.