Diameter: 15/32Diameter 2: 59/64Thickness: 1/16Material: CopperThread Type: SAENominal Size: 7/16Type: Flat WasherBox of 24.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.