Reduces total valve train mass. Great for high lift racing performance builds. The springs are manufactured from the highest quality clean chrome silicone wire, shot peened and heat treated for maximum fatigue life. Kit includes springs, upper collars, lower collars, and valve keys. Max valve lift: .600”. Installed height: 1.510″. Seat pressure 152 lbs. Open pressure: 387 lbs. @ .600” valve lift. Note: Does not include valve guide seals.