Item DescriptionShip your materials with maximum protection using Labelmaster's 275-Lb. Double Wall Corrugated Boxes. These heavy duty 18 x 18 x 18-in. containers are approved for shipping via UPS, FedEx Ground, Parcel Post, truck, rail and express. Shipped and stored flat, they are super-strong, 48-lb. edge crush test (ECT), and twice as strong as 200-lb. test packaging for superior crush- and puncture-resistance, even during the roughest handling. These shipping cartons are sold in bundles of 15.