Columbian Self-Seal Business Envelopes w/Security Tint, #10, 4 1/8 x 9 1/2, White, 100/Box. Dual flap provides added security. White wove finish delivers a professional look and feel. Columbian Self-Seal Business Envelopes w/Security Tint, #10, 4 1/8 x 9 1/2, White, 100/Box