These lower arms replace the factory units to give you more adjust ability in camber. The suspension geometry on the rear of the MR-S chassis usually causes too much negative camber than what is needed when the ride height is lowered. These arms offer the camber adjust ability to get the camber specifications within tolerable numbers. The pillow ball helps with rigidity and reduce any play found in rubber bushings. These control arms are extremely strong for any extreme driving and powder coated with Megan Racing colors..