Fitment Type: Performance/Custom By using inner and outer springs mated together through a slight interference fit and with differing frequencies, Alpha Valve Springs are able to prevent valve float and maintain valvetrain stability at engine speeds in excess of 10,000 rpm Manufacturer Part Number: 344-05-1410 S2000 Honda Skunk2 Alpha Valve Spring & Titanium Retainer Kit - B/D/H/K-series Skunk2 Titanium Retainer Kit Neu, Warranty: Unspecified Length, Brand: SKUNK2