Standard Diameter: 4" / 4.00 InchesMetric Diameter: 101.6mmGrade: 100Material: AISI 52100 Chromium SteelBall Weight (each): 9.45 Pounds / 4.286 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.