This is an RC-scale aluminum rear upper suspension arm built for TAMIYA TT01 and TT01E chassis. The light blue anodized coating takes the place of the stock plastic arm to give a firmer mounting point and a repeatable fit for setup work.
Fitting the arm involves removing the rear wheel hub, detaching the factory upper arm, and securing the aluminum arm with the car's existing mounting hardware. After installation check that the ball stud is seated correctly and that the suspension moves without binding.
In tuning applications the rear upper arm changes rear suspension geometry and the feedback delivered to the chassis. A stiffer aluminum arm reduces flex under load and provides a steadier response through turns, aiding drivers when adjusting rear toe and camber.