Michigan Motorsports .645" LS Dual Valve Spring Kit w/ Steel Retainers Fits 1997-2013 Factory LS Head Castings 4.8L 5.3L 5.7L 6.0L 6.2L Will not fit LS7 or LS9 applications, or aftermarket heads with bronze valve guides. Michigan Motorsports' dual valve spring kits are ideal for camshafts up to .645" lift, which covers the vast majority of aftermarket LS camshaft options. These springs strike the perfect balance of having enough spring rate to control your factory-style LS valvetrain at 7,000rpm, while still being mild enough to provide long life of valvetrain components in daily driver applications. Springs are polished for reduced fatigue and extended service life, while the 2-piece locator/seal design allows for shimming of the seat height if desired. Valve seal installation tool is recommended for easiest installation (click here). The kit includes: 16 x Polished Dual Springs 16 x Steel Retainers 32 x Valve Locks 16 x .045" Thick Locators for stock or .500" OD Guides 16 x Valve Seals for Dual Spring Setups Specs: 155 lbs @ 1.780" 380 lbs @ 1.180" 400 lbs @ 1.130 Coil bind @ 1.100"