Supertech's Beehive form Valve Springs are designed and optimized to reduce valvetrain harmonics, provide greater spring stability, and reduce spring and retainer masses for increase performance and durability in under high RPM and load. The stress levels are kept under control and fatigue is reduced for long durability under extreme conditions- Spring O.D. - 23.87mm / 28.07mm - Spring I.D. - 14.73mm / 18.85 - Seat Pressure - 90 lbs. @38mm - Open Pressure - 225 lbs. @28mm - Rate Inch - 342 lbs. - Coil Bind - 23mm - Max Net Lift - 13.5mm - Spring Material - PAC Alloy