Columbian Manila Envelopes, 9 x 12 Inch, Grip Seal, Mailing Envelopes, 100 Per Box (CO922) Heavy duty 28 lb. opaque brown kraft material provides privacy of contents; open end closure; 9 x 12 inch; 100 envelopes per box Convenient and secure self-sealing Grip-Seal closure; simply peel off release strip and press down for a quick, secure seal A durable all purpose mailing envelope; ideal for mailing documents, catalogs, direct mail, promotional material, brochures and more