Chrome Plated and Polished Silicon-Manganese SteelAll QA1 springs are manufactured using the highest quality chrome silicone. This material offers high strength, consistency and longer life. Cold Wound - Heat Treated - Shot PeenedAll QA1 springs go through intensive manufacturing processes to ensure consistency, accuracy and durability. Squared EndsAll QA1 springs are ground at both ends to ensure straight, consistent and accurate operation. Protective CoatedQA1 springs are either powder coated and chrome appearing for excellent longevity, or are polished and chrome plated for the ultimate in appearance. lengths and Rates MarkedAll QA1 springs are clearly marked with the free length of the spring and spring rate for quick and easy identification. Cold WoundDouble shot-peened, double heat-treated for consistency. Lifetime GuaranteeAll QA1 springs are lifetime guaranteed to remain within 5% of original free height under normal operating conditions. For Superior Quality and Design, Look for QA1 SpringsPit Stop USA offers QA1 Chrome Coil-Over Spring - 2-1/2" I.D. x 12" - 150 lb. 12CS150 at low everyday prices. Be sure to check out all of our products from QA1 Precision Products including QA1 Chrome 2-1/2" I.D. x 12" Tall.