This Prothane complete motor mount set for the 1997-2013 Corvette. These motor mounts have polyurethane bushings with billet aluminum casings. The polyurethane bushings offer a much sturdier surface than the hydraulic mounts. This sturdiness increases engine response and allows for more efficient torque transfer all while being much more durable than the hollow mounts. In much the same way the aluminum casings offer great protection for the new mounts while further enhancing their durability and keeping your weight low.