11 1/4 x 8 3/4 x 12 Heavy Duty Corrugated Boxes ECT-44 25/Case: Heavy-Duty Single Wall Corrugated Boxes are engineered for added durability and stacking strength making them ideal for heavier or more delicate shipments. Constructed from ECT-44 single-wall kraft corrugated material these boxes are 40% stronger than standard shipping containers. They ship flat to save space and are perfect for businesses needing reliable packaging solutions.