a Replaces the OEM valves and valve springs a Steel, nitrided valves for increased durability and less wear under extreme conditions a Stronger valve springs deal with the extra weight of the steel valves a Springs are made from premium chrome vanadium steel for higher performance and durability at high rpm a Kit contains a set of steel intake or exhaust valves plus a set of specially designed valve springs; can be installed using the OEM retainers, bases and valve seals