Titanium 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.