Quality Park 21212 ( QUA21212 ): Security Window Envelopes, Contemporary Seam, #9, White, 500 / Box; Blue tint on the inside for privacy of contents. Wove finish adds a professional touch. Gummed flap provides a secure seal. Envelope Size: 3 7/8 x 8 7/8; Envelope / Mailer Type: Business / Trade; Closure: Gummed Flap; Trade Size: #9. .. QUA21212 or QUA-21212