Sturdy & Reliable: Our document mailer is made from high-quality 300 GSM thick paperboard to protect item from bending, creasing, or crushing during shipping and handling. Self-Sealing: Our rigid envelopes have a convenient peel-and-seal adhesive strip that ensures secure closure without the need for additional tape. Tear Strip for Easy Opening: Built-in tear strip allows for quick and effortless opening of the rigid mailers 9x12 without damaging the contents. White, Professional Look: Our 9x12 rigid mailer gives clean, crisp white finish enhances the appearance of your shipments and adds a professional touch. Ideal for E-commerce: Our cardboard mailers 9x12 are perfect to be used as photo mailers and for sending flat items like prints, brochures, catalogs, magazines, calendars or small electronics with minimal risk of bending Perfect for Subscription Boxes: These stay flat mailers are great for including promotional materials, small merchandise, or subscription-based products that require safe and efficient packaging.