'Spherical Washer, Steel, Black Oxide Finish, Fits Bolt Sizes M6, Male ID 6.4mm, Female ID 7.1mm, Outside Dia 12mm, Thickness 4.2mm, Thickness Tolerance +/-0.2mm, Radius 9mm, B68 Rockwell Hardness, Used To Compensate For Uneven Surfaces, Includes 1 Male Washer and 1 Female Washer, Pair'