The first step to great handling is selecting proper spring rates front and rear. Through years of testing and manufacturing experience, Race Tech has developed a full line of Hi-Performance Springs using the finest materials and processes. RT Springs have the highest stiffness-to-mass ratio in the industry; making them extremely light weight for their particular rate. RT Hi-Performance Spring Features: Extremely accurate rates. The tightest tolerances in the industry. Heat-treated and shot-peened. Preset to eliminate sacking-out. Extremely lightweight. Made in the U.S.A. Note: Shock spring COLOR is NOT guaranteed. Most RT Dual Shock Springs and Street Single Shock Springs are BLACK. Most Dirt RT Single Shock Springs are BLUE.