Competition inner valve spring locator, lower as designed by Leyland ST. It is essential to use bottom inner spring locating collars with all dual springs EXCEPT VSU-100 or VSR-105 springs to prevent breakage caused by the inner spring wandering at high RPM, although we've never used them on ISC-100 or ISS-100 either. 8 required per engine-order individually. The bottom collars for the inner springs are No Longer Required when using our VSU-100 and VSR-105 range of silicone wire springs as they are a slight interference fit and friction damped. These are recommended if using stock style springs on a race engine.