- Featuring XD-15 15 degree Angular Contact cartridge bearings pressed into precision machined aluminum cups that simply thread directly into the BB shell - Deep-groove raceways allow use of maximum sized Grade 3 Silicon Nitride ceramic balls for increased contact area, improved performance, and longevity - Manufactured to the highest standards at the Enduro Bearings production facility in California, USA - Combine corrosion-proof, cryogenically treated nitrogen steel races with Silicon Nitride Grade 3 ceramic balls in a proprietary process that results in the ultimate high performance bearing setup - Unlike other bearings, they only get better with use. As the bearings wear-in, the balls actually make the races even smoother - Lifetime warranty against wear and corrosion