This is the replacement spring for the ACS3 Rock Shox Lyrik/Yari kit. Push uses a super high quality high tensile CrV-SI spring wire, which they claim provides the best possible initial bump sensitivity, as well as predictable control throughout the entire stroke. Available in seven spring rates. This spring is compatible with 2016 - 2018 Rock Shox Lyrik and Yari forks ranging in travel from 150mm to 170mm. Please note, the required spring rate will vary depending on your weight, as well as the current travel of your fork. You can view the Spring Rate Chart by clicking the link above.