21.Size: 1 inch X 2-1/2 inch Outer DiameterMost commonly used and versatile washerIncreases bearing surface and distributes load over a larger areaCan be used to prevent a screw or bolt from going into a hole too farCan also be used as spacers by stacking more than oneSpecification(s) Met: ASME B18.Flat Washer, Fits Bolt Size 1 in ,Steel Galvanized Finish, 5 PK They distribute the force from the bolt head & nut over a larger area which serves to protect the surface of the material you are working with.1.