Aluminum paid off suspension owner the BACKSIDE with this back suspension redesigned with the new HS bulkheads for an expanded array of set-up alterations. The rear suspension system holders make it possible for installation in upright or inverted orientations, leading to additional roll center areas the inner hinge pins. The downward orientation with this suspension holder is employed mainly for Dirt tracks. The upward orientation the suspension system owner is utilized mainly for Carpet tracks. The suspension system holders allow usage of both long or standard suspension system supply configurations. Machined from premium Swiss 7075 T6 aluminum and black coated. Fits XB4'21