Corrugated 150 Pound Test Multi-Depth BookFold Mailer / Shipping Box - Case of 25 Vari-depth design allows for a wraparound snug fit for items up to 3.5 inches thick Interior box dimensions are 9.18 x 12.25 inches allowing for items up to 9x12 inches. 150 pound test corrugated material Designed for books and plaques, but also useful for just about any item requiring extra shipping protection. Case of 25