1203 Full Ceramic Self Aligning Ball Bearing 17mm x 40mm x 12mm PTFE Cage 1203 Full Ceramic Self Aligning Ball Bearings have a spherical outer ring raceway, balls and cage continue to rotate.this type of bearings is suitable when the displacement of the centers around which the shaft and housing rotate and shaft deflection are likely to occur, Bearing is made of Ceramic, inner diameter is 17mm, outer daimeter is 40mm and width is 12mm.