Upgrade your Cummins valve springs and retainers with our Fleece Performance spring and retainer kit. Our springs are manufactured from “super clean” Hi-Tensile Chrome Silicon steel with a proprietary multi-step heat treating process that minimizes load loss. These springs have a seat pressure of 105 lbs with an open pressure of 195 lbs at maximum lift. The retainers are thru-hardened 4140 chome moly steel and have a black oxide finish.