H&R BMW F30 / F32 Super Sport Lowering Spring Set (RWD 320, 328, 330, 335, 340, 428, 430, 435, 440)NOTE: THIS IS NOT COMPATIBLE WITH XDRIVE VEHICLES. Every spring produced by H&R comes from the H&R ISO 9001 certified engineering and manufacturing facility in Germany. All H&R springs are produced from a special 54SiCr6 spring steel, which has strength rated at 290,000 psi resulting in unrivaled tensile strength and resiliency. H&R Super Sport Springs have all the features of Sport Springs, plus additional loweringgreat for the seasoned enthusiast