With full travel hydraulic lifters, higher RPM in performance engines is often limited by the incorrect positioning of the lifter's internal piston, which inevitably "pumps up" during the engine cycle. This improper location results in open valves and therefore leads to lost horsepower and sometimes even engine failure. With COMP Cams Short Travel Race Hydraulic Roller Lifters, the patent-pending design minimizes internal piston movement to cut down on open valve issues and allow higher engine RPM (thus increasing horsepower). The surface of these lifters has been black-oxided to significantly reduce surface friction, wear, and lubrication temperatures. This creates a high-performance, high-quality component.