Machine Key, Tapered Gib Head, End Type Tapered Gib, Material Steel, Finish Plain, Length 4-1/2 In., Square 1/2 In., Head Height 3/4 In., Thickness Tolerance +0.002 In., Length Tolerance -0.100 In., Tensile Strength (PSI) 64,000 psi, Rockwell Hardness B85, Features Tapers 1/8 In. per Ft., Holds Pulleys and Gears on Transmission Shafts