BLOX Racing Valve Springs are wound using super clean, chrome silicone alloy. These valve springs are designed and engineered for both high performance street driving and all-out racing conditions. Each set provides maximum lift while preventing valve float and helps counter the effects of spring surge. These are perfect for naturally-aspirated and forced-induction engines. Easy installation, no machining is required. Recommended for aftermarket, performance camshafts. For maximum results, use with BLOX Racing retainers.