The BSA30 73mm - BB - XD15 Pro - 30mm from Enduro Bearings is a high-quality bottom bracket designed for 68mm BSA framesets and 30mm cranksets. Exclusive to Enduro Bearings, the XD-15 Pro BBs feature XD-15 15° Angular Contact cartridge bearings housed in precision machined aluminum cups that thread directly into the BB shell. These XD-15 Pro bearings are made with Enduro's XD-15 steel, the same material used in their XD-15 Corsa bearings. With a 15° angular contact sealed design and deep-groove raceways, these bearings offer increased contact area and improved performance and longevity. The use of Grade 3 Silicon Nitride ceramic balls further enhances their durability and performance. Manufactured to the highest standards at Enduro Bearings' production facility in California, USA, these XD-15 bottom brackets combine corrosion-proof, cryogenically treated nitrogen steel races with Silicon Nitride Grade 3 ceramic balls. This proprietary process results in the ultimate high-performance bearing setup. With the ability to easily fit Shimano-type 24mm cranks into BSA threaded bottom bracket shells, these thread-in bottom brackets offer a convenient solution without any hassle. And Enduro Bearings is so confident in their product that they offer an unlimited lifetime bearing and race warranty. What sets these XD-15 bearings apart is that they actually improve with use. As the bearings wear-in, the balls make the races even smoother. This means that while other ceramic-hybrid bearings may claim speed and power advantages on day one, the Enduro XD-15 bearings not only provide the same initial advantages but also become faster and smoother over time. In contrast, other ceramic-hybrid options will only become slower. Shell Fitment: BSA Bearings: XD-15 Ceramic Seal Type: LLB Grease: Kluber NBU52 Grease Axle Size: 30mm Warranty: Unlimited Lifetime Enduro Reference Number: BKC-0805