Nominal Size: 5/16"
Inside Diameter: 5/16"
Outside Diameter: 9/16"
Thickness: 1/16"
Material: Steel
Finish: Chrome
Thread Type: AN
Hardness: Grade 2
Style: AN
Type: Flat Washer

Box of 10.

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.