Rotor pf46 bbright ceramic bottom bracketthe new advanced non contact labyrinth seals yield a buttery smooth spin with unparalleled protection against dust water and mud ultra rigid plastic caps give high compression and deformation resistance facilitating crisp shifting available with steel or ceramic bearings constructed of cnc machined 7075 aluminiumfor use with bbright systems to reduce the axle width to 24mm this can be used with rotor 3d agilis cranks features press fit 4624 for bb