The Reflex Racing Mass Damper Set is designed to smooth out your 1/28 scale car by reducing the amplitude of vibration on the front end caused by the uneven nature of RCP Tracks. The mass damper is mounted on the ballast weight hole on any Reflex Racing Carbon Bumper or on the body clip posts of your RX512 Jomurema bumper. The result is a car that is smoother to drive and more controllable at high speed and through bumpy sections. Adjust the Damper by using a different combination of weights and springs.