CeramicSpeed CeramicSpeed Bearing 17287 17x28x7 EaAll CeramicSpeed Bearings are hand built in Denmark. Super smooth CeramicSpeed grade 3 Silicon Nitride balls are matched (within microns) with hardened steel raceways that feature an ultra smooth polished groove. The balls are held in place by a reinforced polyamide cage. Every bearing is optimised with a low viscosity CeramicSpeed Blue Grease to minimise fiction and increase bearing life. Non contact seals complete the bearings, keeping dirt and