The 6318 full ceramic bearing is a ceramic deep groove ball bearing that is widely applied in cryogenic engineering, Medical equipment, high-speed machine tools, optical instruments, high-speed motors, printing machinery, food processing machinery, and more. also, 6318 ceramic hybrid bearings have expanded the application of ceramic bearings. Silicon nitride is type of ball bearing. type 6318z ceramic bearing is single shielded open type bearings, and 6318zz ceramic bearing is Double Shielded on both sides. standard 6318 70 mm ceramic Ball Bearing Inner Dimension is 70mm X Outer Dimension 150mm X Width 35mm, for more custom 6318 ceramic bearings and seal options.