55 mm x 120 mm x 29 mm fag 6311 bearing

FAG Bearing offers a 55 mm x 120 mm x 29 mm fag 6311 bearing MianKang Bearing Co., Ltd. 55 mm x 120 mm x 29 mm selection of Genuine FAG Bearing Open Type Seals or Shields: at Wholesale Prices. We are a 55 mm x 120 mm x 29 mm fag 6311 bearing Certified Parts Retailer

What is 6311 bearing interchange？