Skunk2 Racings Steel Spring Bases for Honda’s K20/ K24 & F20C/ F22C engines are designed to allow all K Series cylinder heads originally equipped with single valve springs to accept our higher-performance, dual valve springs as well as allow F20C/ F22C engine to use the K Series valve springs.Skunk2 designs, develops, and tests its entire valvetrain lineup in-house to ensure superior quality and maximum performance gains. During development, each valvetrain component is tested both on the dyno and the road. Manufactured from the best materials available, Skunk2 valvetrain components provide exceptional performance, reliability, and quality and remain standard-issue on each Skunk2 vehicle that we build and support. NOTE: Skunk2 PN 312-05-0010 (Spring Bases) are used to Install Dual Springs in Single Spring K Series Heads or Install Skunk2 Valve Springs in F20C/F22C Engines.Must Purchase New Valve Seals to install these Springs Bases.