Spherical Washer Assembly Bottom Washer Inside Diameter 0.656 in Bottom Washer Outside Diameter 1.375 in Bottom Washer Radius 1.75 in Dimensional Standards TCMAI Finish Black Oxide For Screw Size 5/8 in Material Steel Maximum Rotation 2 Degrees Maximum Thickness 0.313 in Minimum Thickness 0.313 in Pack Size Small Pack Rockwell Hardness 85 to 90 on 15N Scale Spherical Washer Type Spherical Washer Assembly System of Measurement Inch Top Washer Inside Diameter 0.688 in