Alpha Titanium Retainers are manufactured using the latest 3D CAD (Computer Aided Design) and FEA (Finite Element Analysis) to ensure that each is optimized for strength as well as for reduced weight. Skunk2 engineers then test and prove their designs on the engine dyno as well as the race track. Once approved for manufacturing, only medical - grade titanium that's been ultrasonically inspected and certified is used. Following CNC machining, each retainer is then individually inspected to ensure proper hole diameter, taper, and that each are free from machining defects to ensure proper installed valve spring heights and pressures. Finally, each retainer is serialized for your protection, including valuable information, like material batch specifics as well as production and inspection dates.