Metric Inch PRODUCT SIZEHARDNESSSTANDARDSquare Section Spring Washer3mm to 39mmHV (430 to 530)DIN 7980Flat Section Spring Washer3mm to 39mmHV (430 to 530)DIN 127 BHardened Washer12mm to 30mmHV (300 to 370)IS 2016Hardened Steel Washer12mm to 56mmRockwell 26 to 45 (HDG)Rockwell 38 to 45 (Coated)ASTM F436M PRODUCT SIZETENSILE STRENGTHSTANDARDUSS Plain Washer1/4 to 1 1/2HRC 38-45ASME B18.21.1-ASAE Plain Washer1/4 to 2HRC 38-45 (Coated)HRC 26-45 (HDG)ASME B18.21.1-ASpring-Lock Washer1/4 to 1 1/2HRC 38-46ASME B18.21.1Hardened Washer1/4 to 1 3/8HRC 38-45 (Coated)HRC 26-45 (HDG)ASTM F436