Adjustability is one the most important things when tuning in your street cars suspension. That is why we have taken the time to develop the ultimate on-car adjustable upper control arms for the rear on your GM vehicle. There were no short cuts when manufacturing these arms, only the best materials and components money can buy were used to build our Ultimate Arms. Well known weak areas where other manufactures use mild steel have been replaced with aircraft quality 4140 chromoly steel featuring a TIG welded construction. The upper control arm mounting points feature CNC machined 0.250" mild steel, 4140 chromoly tube adaptors and a high strength 4140 chromoly heat treated 1.000" solid adjuster; truly overkill for any application!