The Enduro Ceramic Hybrid XD-15 Bottom Bracket features XD-15 15 degree Angular Contact cartridge bearings pressed into precision machined aluminum cups that thread directly into the BB shell. The deep-groove raceways allow use of maximum sized Grade 3 Silicon Nitride ceramic balls for increased contact area, improved performance, and longevity. This bottom bracket combines corrosion-proof, cryogenically treated nitrogen steel races with Silicon Nitride Grade 3 ceramic balls in a proprietary process that results in 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. Manufactured to the highest standards at the Enduro Bearings production facility in California, USA, this bottom bracket comes with a lifetime warranty against wear and corrosion.