proflow's pro ls upgraded rocker arms feature high-quality rocker bodies that utilize the factory style pedestal mount. they are made of high-grade 4340 alloy steel to ensure long-lasting durability and performance. this design replaces the factory bearing and powdered metal trunnion and utilizes a captive bearing design and a bearing steel trunnion. these rocker arms are a perfect upgrade for higher rate springs and performance camshafts for the ls engine. proflow's pro ls upgraded rocker arms come preassembled with heavy-duty trunnion kits, which saves you time and the additional cost of an installation tool.