BSA Thread-In, Ceramic-Hybrid, XD-15, Angle Contact, for 68/73 mm BSA frames.Shimano 24 mm cranks and Sram Dub 29 mm cranks.XD-15 Ceramic Hybrid Bearings An Enduro Bearings exclusive, our XD-15 Pro bottom brackets feature XD-15 15° angular contact bearings pressed into precision machined aluminum cups that thread directly into the bottom bracket shell.XD-15 Pro bearings feature deep groove raceways with maximum size Grade 3 silicon nitride ceramic balls to increase contact area and improve performance and longevity.To ensure maximum longevity and performance, Enduro surrounds these super smooth and fast bearings with our XD15 ´´speed´´ grease.No one else in the bicycle industry offers the combination of speed and durability of the XD15 for hubs, bottom brackets and pulleys.Will never rust or corrode, guaranteed for life.