Business Source Heavy-duty Clasp Envelopes, 11-1/2" x 14-1/2", Brown Kraft (BSN36675) Box of 100Heavy duty clasp envelopes feature an open end style and metal clasp with rounded edges. Metal clasp is plated for rust resistance. Flap offers superior gumming to secure contents. 28 lb. General Information Manufacturer: Business Source Manufacturer Part Number: 36675 Brand Name: Business Source Product Name: Heavy duty Clasp Envelopes Marketing Information: Heavy duty clasp envelopes feature an open end style and metal clasp with rounded edges.