Spherical Washer Bottom Washer Inside Diameter 0.438 in Bottom Washer Outside Diameter 0.875 in Bottom Washer Radius 1.25 in Finish Black Oxide For Screw Size 3/8 in Material Steel Maximum Thickness 0.25 in Minimum Thickness 0.25 in Pack Size Small Pack Rockwell Hardness C40 Spherical Washer Type Spherical Washer Assembly System of Measurement Inch Top Washer Inside Diameter 0.406 in Top Washer Outside Diameter 0.875 in 1 Pair