USS Plain Round Flat Washers are a general purpose steel flat washer suitable for use in many Construction and MRO applications. USS dimension washers, having a bigger outside dimension than their SAE counterparts, provide an increased load bearing surface that distributes fastener clamp load over a larger area and assists in providing a secure, trouble-free connection. USS flat washers are made to the dimensional requirements of ASME B18.21.1 Type A Wide Series, Regular. They are manufactured of Low Carbon Steel and are supplied plain/uncoated with a light protective oil finish.