Part# ST2031 - Yella Terra Street Terra shaft type roller rocker set to suit Holden 186 and 202ci Red motors and 3300 Blue and Black motors. Direct bolts on with no machining required. Economically priced, entry level rollers that have a strong vacuum die formed light weight arm designed for high performance street and budget race applications that do not have excessively high valve spring pressures. For use with hydraulic camshafts. Includes 5/16 shafts, adjustable valve lash and rocker arm ratio is 1.5 : 1