BC Racing Replacement linear springs for BC Racing Coilovers. BC Racing linear springs are an industry standard 62mm I.D. (inner diameter.) Each spring is manufactured of SAE9254 steel with zinc undercoating and outer powder coating to ensure rust does not penetrate the metal of the spring and compromise performance or reliability. The BC Racing linear spring comes in many different lengths and rates to suit consumer demand. Linear springs are available from 120mm length through 260mm length. Spring rates range from 3K to 20K. If you need a higher spring rate, then you must purchase Swift Springs which go up to 40K. Note: Includes a total of one (1) spring. Additional Notes All sales are final on this product. Please ensure you are selecting the right specs when customizing your coilovers. It's highly recommended to ensure your struts are valved for the rates you are choosing. If you change the spring rates by 4k or more, it's also recommended to change the valving. Failure to properly pair your springs and struts can damage your coilovers, hinder performance, and reduce ride quality.