CHEVROLET LS1. This kit includes PAC 1209X Dual Spring (x16), Kelford Titanium Retainer (x16), Steel Locator (x16) and Viton stem seal kit (x16). PAC-1209X RPM Series Dual Spring set of 16. Premium quality Japanese spring steel wound in USA by PAC. Made with advanced heat treatment processing and surface finishing techniques (nano peening) to extend fatigue life. High spring frequency to allow for better spring surge control at high rpm. 160lb at 1.800″ installed height. 485lb at 0.650″ valve lift. Coil bind (spring solid height) 1.000″.