Over double the strength of the OEM shafts. Precision ground from 4140HT steel, gas nitrided and final surface treated. Replaces the stock rocker arm shaft to rocker arm tower bolts. The one time installation of these studs help prevent damage to the rocker arm tower bolt threads and subsequent damage when rocker arms come loose. Especially advised when running high lift cams. Kit includes 4x rocker arm shafts, 8x studs, 8x 12-point nuts.