BOX USA Stayflat Flat Mailers are designed for shipping documents, photos, artwork, and printed materials. These rigid envelopes are made from chipboard to help keep contents flat during shipping and handling. The stay-flat design helps reduce bending of items such as certificates, photographs, catalogs, or prints without the need for additional inserts or stiffeners. Each mailer is designed to provide structure while remaining lightweight. Compared with standard paper envelopes, rigid chipboard mailers provide additional support for flat items while maintaining a slim profile suitable for many mailing applications. These envelopes can be used with USPS First Class, Priority Mail, and commercial shipping carriers depending on package weight and dimensions. Each mailer includes a peel-and-seal adhesive strip designed for quick packing and closure. The adhesive flap helps keep the envelope closed during transit and simplifies packing for shipping or fulfillment tasks. BOX USA flat mailers are available in bulk packs and are commonly used by e-commerce sellers, fulfillment centers, print shops, offices, and classrooms. They can be used for mailing brochures, photos, invoices, product literature, artwork, proofs, promotional materials, magazines, calendars, and other flat items. Available in multiple sizes, BOX USA Stayflat Mailers can be used for mailing single items or larger quantities of documents and printed materials. These mailers can be paired with other BOX USA shipping supplies such as thermal labels, packing tape, bubble mailers, and corrugated boxes to support packing and shipping operations. BOX USA Flat Mailers provide a rigid chipboard envelope option for mailing flat materials while maintaining a lightweight packaging format.