Lightweight yet ultra-strong back upright molded from unique INTENSE composite material. Features larger outside 8x16x5mm ball-bearing for increased dependability and life-span. Makes the trunk of car really stable. Improves bump taking in and managing in hotter conditions. Fits XB8, XB8E, GTX8'19 and newer, GTX8E'19 and more recent, XT8'19, XT8E'19