Manley Pro Series I-Beam Turbo Tuff connecting rods are assembled from high-quality 4340 forged steel. Every rod is fully machined to the highest standards, and the Turbo Tuff design combines the appropriate weight and rugged strength for ultimate horsepower utilization. Each rod is shot-peened after machining and individually magnafluxed. These connecting rods feature 3/8 in. ARP 2000 cap screws with 12-point heads for outstanding 200,000 psi tensile strength. Manley Performance was founded by Hank Manley in 1966, his desire for speed and to win led him to build his own racing engines. Since that time Manley has continued to evolve, using the knowledge they have gained since the beginning and building on that to continue to bring the best engine components to the market. The goal at Manley Performance remains laser focused on designing and producing the highest quality internal engine components at extremely competitive prices coupled with excellent customer service.