RockJock's 4-inch lift coil springs for 1997-2006 Jeep TJ Wranglers and LJ Unlimiteds replace factory springs and are designed to work with RockJock Johnny Joint suspension systems or other manufacturer's lift kits. This set features our standard rate front springs and increased-rate rear springs for improved ride and vehicle height control when loaded. Extensive research was done by RockJock to develop the perfect combination of rates and quality of the coil springs. The results: they provide the best in comfortable ride and excellent performance off-road. Powder coated finish. If you need help choosing the correct springs for your Jeep - just call the RockJock sales staff!