This Hyperco coil-over spring has a 2.50 inch inner diameter and a 12 inch free length and has 300 pounds spring rate. Great looking blue powder coat finish and made from high-quality steel. These coil-over springs are part of Hyperco's optimum body diameter spring program. Hyperco optimum body diameter racing springs feature a design concept that adjusts the body diameter of the spring relative to the end coils. The optimum body diameter design enables Hyperco to take full advantage of its high tensile material by optimizing the applied stress through adjusting the spring's body diameter. The result is more deflection for the same free length and spring rate and less weight for the same free length and spring rate and increased rate linearity for the same free length and spring rate and more resistance to bowing. Optimum body diameter springs fit all standard hardware.