Feature XD-15 15degree Angular Contact cartridge bearings pressed into precision machined aluminum cups that simply thread directly into the BB shell Feature deepgroove raceways allowing for maximum sized Grade 3 Silicon Nitride ceramic balls for for increased contact area and improved performance and longevity Manufactured to the highest standards at the Enduro Bearings production facility in California, USA Combine corrosionproof, 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 wearin, the balls actually make the races even smoothe Lifetime warranty against wear and corrosion Third party online sales strictly prohibited by manufacturer