Arbor Spacer Low Carbon Steel Full Hard Temper Thickness 0.002 In Thickness 0.051 mm Thickness Tolerance +/-0.0002 In Inside Dia 1 3/4 In ID Tolerance +0.011 In Outside Dia 2 3/4 In OD Tolerance +/-0.002 In Keyway Width 7/16 In Keyway Depth 3/16 In Tensile Strength 80 000 PSI Rockwell Hardness B90 Meets AISI 1008-1010 Package 10