Hardness RB 90-100Shims refer to a broad class of specialty flat washers that are used for positioning and spacingWhile shims look like flat washers they are different in that shims are typically made from non-ferrous materials, using more precise materials and production techniquesFinish: Plain Item: Shim Stock Length: 18 Inch Material: Full Hard AISI 1010 Steel Measurement: Inch Origin: Imported Shim Length Maximum: 18.060 Inch Shim Length Minimum: 17.940 Inch Thickness: 0.0250 Inch Thickness Maximum: 0.0260 Inch Thickness Minimum: 0.0240 Inch Type: Flat Width: 6 Inch Width Maximum: 6.060 Inch Width Minimum: 5.940 Inch 