Tapered Machine Key, Gib Head, Steel, Plain Finish, 4 In Length, 5/8 In Square, 1 In Head Height, +0.002 In Thickness Tolerance, -0.100 In Length Tolerance, Tensile Strength 64,000 Psi, Rockwell Hardness B85, Tapers 1/8 In Per Ft, Holds Pulleys And Gears On Transmission Shafts