Aluminum Rear Lower Suspension Holder BACK for semi-split bulkheads provide an expanded selection of set-up corrections. The aluminum suspension holders feature Integrated Suspension Settings™ (I.S.S.) that allows for fast & effortless suspension system geometry environment. Using eccentric suspension bushings placed into aluminum suspension holders – including additional suspension shims – the XB8 suspension geometry are completely modified in only seconds. Machined from premium Swiss 7075 T6 aluminum and black coated.