ARP's L19 material (comparable to A1 Technologies H11 Tool Steel) is a premium steel that is processed to deliver superior strength and fatigue properties. L19 is a very high strength material compared with 8740 (standard ARP headstuds) and is capable of delivering a clamp load at 260,000 psi. It is primarily used in short track and drag racing applications where inertia loads exceed the clamping capability of ARP2000. Like most high strength, quench and temper steels - L19 requires special care during manufacturing to avoid hydrogen embrittlement. This material is easily contaminated and subject to stress corrosion. It must be kept well-oiled and not exposed to moisture. These come packaged individually wrapped in a special wax paper to prevent contact with moisture until ready to be used.