SAE thru-hardened steel flat washers are typically used with Grade 8 Bolt and Nut assemblies to increase the load bearing surface area under the head of the bolt or nut while providing a smooth hard surface for the nut to be tightened down onto. They are made to the dimensional requirements of ASME B18.21.1 Type A Narrow Series and meet the material requirements of ASTM F436 for heat treated, quenched and tempered steel round flat washers with a thru-hardness (core) of Rc 38-45. SAE dimension flat washers have a smaller outside diameter and are stamped from thinner gauge steel plate than the equivalent sized commercial USS (U.S.Standard) flat washer. SAE washers are often used under bolt heads and with hex nuts when there is less clearance around the fastener head or a limited bolting surface is available. Washers are manufacturer stamped for identification and traceability.