... and corrosion resistance,lubricaton and maintenance free when working,especially high and low-temperature application.etc.could be used in awful ... and specially condition.The rings and balls made by full ceramic material:Zr02,as a standard constructure,the cage made by ... ,PEEK,PI,AISI SUS304,SUS316,Cu,etc. 6901-2RS Full Ceramic sealed Ball Bearing, the inner diameter is 12mm, outer diameter ...