Lightweight yet ultra-strong back upright molded from unique INTENSE composite item. Features bigger outside 8x16x5mm ball-bearing for increased dependability and life-span. Makes the trunk of vehicle extremely stable. Improves bump consuming and managing in hotter conditions. Fits XB8, XB8E, GTX8'19 and much more current, GTX8E'19 and more recent, XT8'19, XT8E'19