USS dimension thru-hardened flat washers are typically used with Grade 8 Bolt and Nut assemblies to provide a larger surface area under the head of the bolt or nut while providing a smooth hard surface for the nut to be tightened down onto. USS Flat Washers, having a bigger outside dimension than their SAE counterparts, will provide a larger bearing surface area in high stress applications. Using the largest washer possible provides for better distribution of the clamp load, which assists in providing a secure, trouble-free connection. USS thru-hardened steel flat washers are made to the dimensional requirements of ASME B18.21.1 Type A Wide 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. Washers are finished with a Zinc Yellow Dichromate plating for corrosion resistance. Washers are manufacturer stamped for identification and traceability.