These silver powder, high travel springs are made to fit with QA1's 4th Generation F-Body Pro Coil Systems. With a 2.125" upper I.D. and 2.5" lower I.D., they are offered in 3 rates with a 15" free length. Made in the USA, these high travel springs have fewer coils and a smaller wire diameter. As a result, they are lighter and have increased travel due to the larger distance between the coils. These lighter springs reduce unsprung weight and react faster, optimizing suspension performance. In addition, this high-grade material, along with careful heat-treating and post-processing, allows for greatly improved fatigue life, and the coil design allows the springs to be compressed to coil-bind without affecting spring rate or free height. All QA1 springs are manufactured using the highest quality materials for high strength, consistency and long life. They are cold wound, heat treated and shot peened to ensure consistency, accuracy and durability. All QA1 springs are ground at both ends to ensure straight, consistent and accurate operation. They are either silver powder coated for excellent longevity, or are polished and chrome plated for the ultimate in appearance. Lengths and rates are clearly marked for quick and easy identification. All QA1 springs are lifetime guaranteed to remain within 2% of the original free height and rate under normal operating conditions.