Standard Diameter: 7/32" / .21875 InchesMetric Diameter: 5.55625Grade: 5Material: Si3N4 Silicon NitrideBall Weight (each): .01041 Ounces / 0.295 GramsSilicon Nitride (Si3N4) Ceramic Balls are formed from a new material suitable for applications where high loads, high speeds and extreme temperatures are factors. Long life and the need for minimal lubrication make this material appropriate for extreme applications. Silicon nitride is a non-porous, non-magentic, non corrosive, and lighter than stee