Features an oil metering design that provides uniform metering throughout the entire rpm range Rollers and axles are manufactured from high-carbon/chromium bearing-quality steel, which is through-hardened for improved wear and load carrying capability, and the pushrod seat is carbo-nitrided Each unit is 100% tested for proper function Adjustable pushrods required Pro-Magnum hydraulic roller lifter is designed to perform at higher engine speeds as in race application, and a slight increase in noise should be expected; unique anti-pump-up retainer is designed to replace the stock spring retainer clip, which precisely limits plunger travel