<p>MIDWEST FASTENER Flat Washer, 1/2 in Dia Inside, 1.378 in Dia Outside, 0.109 in Thick, 2 Grade, Galvanized Steel, Package Type: Box, Package Quantity: 50.</p> <p>A flat washer is a thin, usually round, plate with a hole in the middle that is normally used to distribute the load of a threaded fastener. USS flat washers have a large, wider body. SAE flat washers are machined to a tighter specification and have a smaller outside diameter.</p>