Steel top collars. Standard size replacement; installs without machining. Kit includes Race Master valves; performance double spring assemblies; steel or titanium top collars and a complete set of Manley''s fully machined chromoly valve keys. Race Master valves are manufactured of stainless XH-426 for exhaust and stainless NK-842 for intake and offer great ultimate tensile strength; combining superior quality at a competative price. Okay for stock or racing upto 8000 RPM.