Wiha 75709 - System 4 Torx Bit T9 x 28mm. High alloy chrome-vanadium-molybdenum steel, hardened, on 4 mm hex stock.
CVM or Chrome-Vanadium-Molybdenum steel is a special, high strength, high performance alloy. Chromium improves wear resistance, hardness and corrosion resistance. Vanadium also improves the grain structure for a tougher tool. Molybdenum improves impact resistance as well as increases tensile strength and elasticity to prevent tool breakage and snapping.
WARNING: Cancer and Reproductive Harm—www.P65Warnings.ca.gov