RaceMax Vertical Bar Chevrolet Mark IV, Gen 5/6 Mechanical Roller Lifters For the racer who wants a lifter they can rely on with added features. Heat-treated 8620 steel billet bodies. Bodies are CNC machined in one process to assure accuracy of all part features. Increased oil ban diameter for maximum rigidity. Precision ground for proper fit in O.E. and +.300” tall aftermarket lifter bores. Heat treated tool steel nitrided axles and precision fitted roller bearings. Pressure fed axle oiling insures longevity and best defense against premature failure. Made in the USA!