Standard Diameter: 2-1/2" / 2.5 InchesMetric Diameter: 63.5mmGrade: 100Material: AISI 52100 Chromium SteelBall Weight (each): 2.315 Pounds / 1.05 KilogramsChrome steel balls offer the precise geometry and fine surface finish that makes them especially useful for bicycles, casters, drawer slides, door locks and many other applications.