Shimano BB-MT800 Pressfit Bottom Bracket XT has gone 11-speed, and the new Shimano XT Cranksets are spinning on XTR/Dura-ace inspired bottom brackets. They have a smaller bearing size to enhance rolling efficiency and for shaving some weight. They are also better sealed to reject whatever muck mother earth conjures up and tries throw at them. Shimano BB-MT800 Pressfit Bottom Bracket Features: Small Ball Bearings for Better Rotation Better Sealing Fits Press Fit 92mm BB Shells | Shimano | Bb-Mt800 Pressfit Bottom Bracket Pf Bb, Comes With 3X2. 5Mm Spacers