Xray X12’21 matched front coil springs
Xray have introduced two new options for matched front coil springs for the X12’21 with black and gold joining the kit standard silver. The new springs offer a softer and harder option to the silver and have been developed through extensive testing and racing experience. Stiffness is controlled by the thickness of the wire and also by the number of coils with the gold softer springs having a lower C value, while the black stiffer springs have a higher C value.
Source: Xray [teamxray.com]