CeramicSpeed cartridge bearings are an upgrade option for any cycling discipline. These bearings provide extremely low friction, improved power transfer, and a service life that far exceeds traditional steel bearings.Grade 3 Silicon Nitride ballsHardened steel racesReinforced polymide cage and non-contact seal to keep dirt and moisture outHigh resistance to poor lubricationCan be used for any cycling disciplineSold as eachHand built in DenmarkItem SpecificationsBearing I.D. (mm)12Bearing O.D. (mm)21Manufacturer Number61801 (6801)MaterialCeramicThickness5 CeramicSpeed Cartridge Bearings Cartridge Bearing EAN: 5711050000524