18 x 18 x 18" Heavy-Duty Boxes. Heavy-duty construction provides greater protection and stacking strength. Boxes are manufactured from heavy-duty 275#/ECT-44 single wall kraft corrugated. These cartons are 40% stronger than standard shipping containers. Corrugated boxes are reusable and recyclable. Cartons are sold in bundle quantities and ship flat to save on storage space and shipping. Proudly made in the USA!