Heavy duty construction provides greater protection and stacking strength. Cartons are sold in bundle quantities and ship flat to save on storage space and shipping. 275# Double-wall/ECT-48 (Edge Crush Test) - holds up to 100 lbs. Heavy-Duty boxes provide added protection to ensure that your shipments arrive safe. Meets most mailing and shipping carrier specifications. Contains a minimum of 30% recycled content. Staples Brand 100% Satisfaction Guaranteed. Double Wall Boxes are manufactured from heavy duty 275#DW/ECT 48corrugated. Dimensions: 24"x24"x12". Capacity (Cu. Ft. ): 4. 10/Bundle. Twice the protection of a standard carton.