Our 48 x 24 x 12 Heavy Duty Corrugated Boxes are super strong and heavy duty Double Wall/ECT-48 kraft corrugated carton with twice the protection of a standard carton. ECT stands for Edge Crush Test. The Heavy Duty Double Wall 275 ECT-48 Cartons are sold in bundle quantities and ship flat to save on storage space and shipping. 48 x 24 x 12 Heavy Duty Double Wall boxes with heavy-duty construction provides greater protection and is perfect to use when extra stacking strength is required. Designed to protect your large-size valuable items, fragile, or heaviest items.