Structural Flat Washer, Steel, Hot Dip Galvanized Finish, Fits Bolt Sizes 1 1/8 In, Inside Dia 1 1/4 In, Outside Dia 2 1/4 In, Thickness 0.136 to 0.177 In, Rockwell Hardness C26-45, Used For Structural Leveling, For Use With A325 and A490 Bolts, Meets/Exceeds ASTM F436, Package 10