Set of two included at this price.
Side Crush Structure. This module is made from an alloy of aluminum softer than the chassis’s 6061-T6, so that their fail strength is lower than the chassis yield strength. This allows the crush structure to mushroom and then flatten against the chassis, absorbing a tremendous amount of energy, before the chassis even starts to yield. Typically, these are 6063 alloy aluminum but this does vary by aluminum availability in the locality where each are made.