Standard Diameter: 1/2" / .50 InchesMetric Diameter: 12.7mmGrade: 25Material: AISI 52100 Chromium SteelBall Weight (each): .2952 Ounces / 8.369 GramsChrome 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.