... We are producer for silicon nitride grinding ball/silicon nitride bearing ball/ziconia ball/alumina ball/ceramic ball, and is located in beijing.We ... Grade 3 and Grade 100. Usage: For bearings, inspection, grinding,and other rolling conditions. Specifications of Silicon Nitride balls: ... 4) Capacity: 3,000,000pcs/month,own 200sets grinding equipment5) Diameter: 2mm ~40mm6) Precision: G5 ~ G100