Quality Park No. 10 Double Window Security Tint Envelopes - Security - #10 - 4 1/8" Width x 9 1/2" Length - 24 lb - Gummed - White - 500 / Box No. 10 Double Window Security Tinted Business Envelopes use a gummed closure for dependable performance. Side seam construction is modern and professional. Premium security tint ensures privacy is preserved during mailing. 24 lb. bright-white stock gives mailings a clean, crisp look. Left-side, double windows are perfect for displaying sender and receiver addresses.