12 x 12 x 12 Double Wall Corrugated Boxes ECT-48 (Heavy Duty) 15/Case: These Double Wall Boxes sold in cases of 15 provide extra protection to ensure your shipments arrive securely. Constructed from heavy-duty D.W./ECT-48 kraft corrugated material these boxes deliver exceptional strength and durability. Their double-wall design enhances stacking strength making them suitable for heavy or fragile items. Conveniently shipped flat they save on storage space and shipping costs.