These Light-Duty Boxes, formally known as Value Line Boxes and also known as Cube Boxes or Stack-Rated Boxes, have a thin corrugated wall designed for stacking strength. Box strength is measured using the Edge Crush Test (ECT); the corrugation used in these boxes can withstand 32 pounds per square inch (32 ECT). Box contents should not exceed 35 lbs. Boxes meet ASTM-D5118.