High quality Manzo lowering springs are constructed of SAE 9254 Cold Wounded Steel. One of the strongest and most durable material for car suspension out there. The high tensile strength and phosphate powder coating delivers outstanding spring rates that are extremely durable and resist premature “sagging”. The result is a spring that specifically offers race performance handling, yet maintains smooth and comfortable ride characteristics. Carefully matched springs rates provide exceptional handling, response, control and balance. These springs offer a generous drop to your car while remaining very usable on the streets by having enough clearance to avoid bottoming-out; and the lowered center of gravity improves performance and increases stability, as well as enhancing the appearance of the vehicle. (Note: Spring rates and drop amount vary by different vehicle application and chassis load.)enhancing the appearance of the vehicle. (Note: Spring rates and drop amount vary by different vehicle application and chassis load.)