Zerø ceramic bearings feature ceramic balls and steel rings. The silicon nitride balls (Si3N4) are grade 3 and are among the roundest balls available without a military license. The rings are treated with a black oxide coating that helps prevent rust in the bearing. After this treatment, the race rings are polished to a high gloss. Finally, they undergo cryogenic treatment before assembly to enhance strength. Additionally, we use VV silicone seals, the lightest seals on the market. Dimensions: 24x37x7.