Clean, crisp look conveys a professional image. Flap-Stik® peel-and-press flap seals securely. Quality Park?. Redi Strip Security Tinted Envelope, #10, 4 1/8 x 9 1/2, White, 50. 2-Window Security Tinted Check Envelope, #8 5/8, 3 5/8 x 8 5/8, Wh.