Business Source Heavy-duty Clasp Envelopes - Clasp - 8 3/4" Width x 11 1/2" Length - 28 lb - Clasp - Kraft - 100 / Box - Brown Kraft - Heavy-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.