9 x 11.5 flat mailers offer a range of benefits that make them an excellent choice for businesses and individuals looking to send flat items. Their protective features, cost-effectiveness, convenience, and professional appearance make them a reliable and efficient packaging solution. Whether you’re sending documents, art prints, or photographs, flat mailers ensure that your items arrive safely and in the same condition they were sent. Photo flat mailers are specialized envelopes designed to protect photos, artwork, and other flat items.