Quality Park Reveal-N-Seal Self Seal Security Tinted #10 Double Window Envelope, 4 1/8″ x 9 1/2″, White, 500/Box (1014438). Made from 24# White Wove for durability. Our dependable Reveal-N-Seal patented envelope design has a unique flap that folds up and into place for a firm seal that won’t close and stick prematurely; plus, no peel-strip waste to clean up!