Product details:

Valve SpringSP-SeriesDual Spring/Damper435 lb/in Spring Rate1.160 in Coil Bind1.530 in ODSet of 16The SP series utilizes Hi-Tensile Chrome Silicon outer spring material. For applications with radical cams and/or moderately high rpm, where traditional chrome silicon springs prove inadequate, the SP series is the next highest level of endurance. All SP series springs are Spintron Test-Proven up to 8000 rpm for 700 racing miles.