All CeramicSpeed bearings are hand-built in Denmark. The super-smooth CeramicSpeed grade 3 silicon nitride balls are matched (within microns) to hardened steel rolling raceways featuring an ultra-smooth polished groove. The balls are held in place by a reinforced polyamide cage. Each bearing is optimized with a low-viscosity CeramicSpeed "Blue Grease" to minimize friction and increase bearing life. Non-contact seals complete the bearings, keeping out dirt and moisture. CeramicSpeed bearings can be used for any cycling discipline: Road, Time Trial, Triathlon, Track, Cyclocross, and MTB. The benefits are super-reduced friction, better power transfer, and increased bearing life. During the build process, we check each bearing four times by hand to ensure all parts are perfectly matched. CeramicSpeed Balls are 400% smoother, 128% harder, and 58% lighter than the standard steel bearings typically used in the cycling industry. Comparing CeramicSpeed Balls to other ceramic balls in the industry, you will find that CeramicSpeed Balls are 15% harder, withstand 99% higher loads, and are 100% smoother.