9" x 12" Stay Flat Envelope

The 9 x 12 stay flat envelope is the industry standard size for B2B document and print shipping, and the Flextribe version is built to live up to that reputation. Made from 420 GSM heavy duty cardboard, this 9 x 12 rigid mailer refuses to bend, crease or buckle through carrier sorting machines, weather or rough handling. The white, label-ready finish takes ink, stamps and shipping labels cleanly, which keeps your team moving when high order volumes come through.

Inside, the 9.04 by 12 inch dimensions give 8.5 x 11 letter size paper a snug, protective fit, while the 1.575 inch flap folds back enough to load contents quickly without fighting the envelope. The self-adhesive seal strip closes each 9 x 12 mailer in seconds without tape, scissors or extra tools, which compounds into real time savings when you are processing 100 or more shipments a day. A built-in tear strip on the back gives recipients a clean opening, so the unboxing stays damage-free and presentable, an underrated detail for businesses where packaging signals brand quality.

This size is the right pick for offices, print shops, photographers and ecommerce brands that ship 8.5 x 11 documents, 8 x 10 photo prints, lookbooks, magazines or product flyers on a regular schedule. Every pack ships with 200 free Do Not Bend stickers so carriers handle these packages with care. The cardboard is fully recyclable, and bulk pack sizes (including the 340 count case) are priced to bring the per mailer cost down significantly for fulfillment centers and high volume shippers who depend on the 9 x 12 stay flat envelope as a workhorse SKU.

• Industry standard 9 x 12 size fits 8.5 x 11 documents, 8 x 10 prints and magazines snugly
• Heavy duty 420 GSM 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
• Bulk case pack of 340 brings the per mailer cost down for high volume fulfillment

• Fulfillment centers and warehouses shipping 8.5 x 11 documents and prints at high volume
• Offices and law firms mailing letter size documents, contracts and signed agreements
• Print shops fulfilling 8.5 x 11 document print orders and certificates
• Photographers shipping 8 x 10 portrait prints, proofs and portfolio samples
• Ecommerce brands mailing lookbooks, magazines, catalogs and oversized product inserts