Alloy Steel Round Tube, Material Alloy Steel, Material Grade 4130, Fabrication Seamless, Heat Treatable Heat Treatable, Heat Treatment Air-Hardened, Mechanical Finish Mill, Inside Diameter 1.874 in, Outside Diameter 2 1/4 in, Overall Length 4 ft, Wall Thickness 0.188 in, Yield Strength 63,000 psi, Machinability Not Rated, Rockwell Hardness 92 HRB, Appearance Metallic, Application Fasteners, Gears, Structural Frames, Brinell Hardness 197 BHN