CalOffroad Heavy Duty Platinum Series Front Coil Springs are designed and manufactured to suit Fox coilovers and any other brand running a flat top flat bottom 16 inch coil. Our coils are developed and manufactured in Australia, using high-grade Australian made steel and utilising the latest tapered wire technology, allowing us to tune a rebound rate into the coil, assisting the shock for a less aggressive rebound and less shock fade under extreme conditions. Dyno testing has been carried out to ensure the coil rate is tuned to match the shock valving, achieving the smoothest possible ride. These coil springs are a must have for any truck running a bullbar, winch or any accessory with a heavy front load, as they will support the extra weight on your truck, as well as maintain its height.