Hybrid ceramic ball bearings use a combination of traditional stainless steel rings precision matched with silicon nitride (ceramic) balls. In addition to being excellent electric insulators, hybrid bearings have a higher speed capability and will provide longer service life than all-steel bearings in most applications. We use high precision Si3N4 balls for high speed. Sizes range from 6801-6806 also known as (61801-61806) available in 2RS (Rubber Sealed).