9" x 12" Stay Flat Envelope with Reinforced Strips

The 9 x 12 stay flat envelope with reinforced strips is built for shipments that need a little more structure than a standard rigid mailer can offer. The reinforcement strips give the 9 x 12 mailer extra rigidity along the body and edges, which matters when you are shipping heavier prints, multi-page document stacks, framed thin items or anything that puts more stress on the envelope walls during transit.

Underneath the reinforcement, this is still a 420 GSM heavy duty cardboard mailer with the dimensions and fit you expect from a 9 x 12 stay flat envelope. The 9.04 by 12 inch inside cavity holds 8.5 x 11 documents and 8 x 10 photo prints snugly, the 1.575 inch flap folds back for fast loading, and the white, label-ready finish takes ink, stamps and shipping labels cleanly. The self-adhesive peel and seal strip closes each 9 x 12 reinforced mailer in seconds without tape, and a built-in tear strip on the back gives recipients a clean, damage-free opening.

This is the right pick when standard 9 x 12 mailers feel slightly under spec for what you are shipping: heavier print stacks, layered document sets, premium photo prints, framed certificates or anything where the recipient experience justifies a small upgrade in materials. Print shops, photography studios shipping premium products, and ecommerce brands sending higher value flat goods all benefit from the extra rigidity. Every pack ships with 200 free Do Not Bend stickers, the cardboard is fully recyclable, and the bulk pack of 100 keeps the per mailer cost reasonable while delivering a noticeably more substantial shipping experience.

• Reinforced strips add extra rigidity for heavier prints, document stacks and premium shipments
• 420 GSM heavy duty cardboard keeps contents perfectly flat through carrier handling
• 200 free Do Not Bend stickers included in every pack for carrier visibility
• Self-adhesive peel and seal strip closes each mailer in seconds, no tape needed
• Built-in tear strip on the back gives recipients a clean, damage-free unboxing

• Print shops shipping heavier print stacks, layered documents and premium runs
• Photography studios mailing premium portrait prints, framed thin items and gallery samples
• Ecommerce brands shipping higher value flat goods that justify upgraded packaging
• Offices mailing thicker contract sets, signed legal binders and multi-page agreements
• Art sellers shipping limited edition prints, signed posters and certificate of authenticity bundles