As with all other parts in the valvetrain, the area where the spring sits also takes a beating. The old standard shims simply will not hold up to the extreme spring pressures and high RPMs found in racing engines being built today. COMP Cams® offers a simple but effective solution to this nasty problem. a thin, hardened steel alloy seat which will not only protect the head and shim, but also locate and hold the spring in place. Previously, this part has been available only in a cup form with the retaining portion being on the outside of the part. This required that the head be machined a great deal to accept this cup. a new cup with the locating shoulder on the inside is now available.Pit Stop USA offers Comp Cams Valve Spring Cups - Outside,Steel,.060" Thick,1.730 "O.D.,.640 "I.D.,1.650 "Spring O.D.,Set of 16 4702-16 at low everyday prices. Be sure to check out all of our products from Comp Cams including Comp Cams Valve Spring Seat Cups.