.660" Lift Dual Spring Kit for LS engines using stock rocker arms. Includes dual polished springs, matching titanium retainers, your choice of locators for stock or bronze guides, locks and seals. Spring specs are 155 lbs @ 1.780", 380 lbs @ 1.180", 400 lbs @ 1.130, coil bind @ 1.070" This is a drop in spring kit for LS9 engines, will not fit other LS engines.