Burst strength is a measure of how much pressure it takes to push through the linerboard of a piece of corrugated board, and it is closely related to the tensile strength of the linerboard. Edge crush test (ECT) is a measure of how much pressure it takes to crush the corrugated board by pressing downward on it while it's standing on its edge. ECT is related to the overall stiffness of the linerboards and the corrugating medium that together make up a piece of corrugated board, and it was designed as a better indicator of a box's stacking strength. Corrugated shipping boxes are rated for burst strength or ECT, and the rating is part of the box manufacturer's certificate (BMC) stamped on the box.