These tubular arms are designed to give you 5.5 degrees of positive caster, giving you that straight line stability at high speeds. The tubular upper arms are made of 4130 Chromalloy, and billet aluminum shafts. The bushings are designed out of delrin plastic and are completely greasable which allows the shaft to rotate under light pressure, this allows very fast weight transfer. The arms are also light weight and with the ball joints installed you can drop three pounds of each side. Get an edge over your competition with these Global West tubular upper arms.