Spherical Washer Bottom Washer Inside Diameter 0.813 in Bottom Washer Outside Diameter 1.625 in Bottom Washer Radius 2.25 in Finish Black Oxide For Screw Size 3/4 in Material Steel Maximum Thickness 0.375 in Minimum Thickness 0.375 in Pack Size Small Pack Rockwell Hardness C40 Spherical Washer Type Spherical Washer Assembly System of Measurement Inch Top Washer Inside Diameter 0.781 in Top Washer Outside Diameter 1.625 in 1 Pair