Full ceramic bearing mand Si3N4 have some better performance than Zr02,the rings and balls mand by full ceramic material:SiN4,as a standard constructure,the cage mand by PTFE,generally we also could make the cagr with GFRGA66-25,PEEK,PI,Phonemic Textiles Tube,etc.Compares than the material of Zr02 ,The SiN4ceamics bearings could endure heavier load and could be used in hingher temperature environment.Also we could offer precision ceramic bearing which generally used in high-speed and high-rigidity spindle.the manufactured clearance could be P4 TO UP grade