For use with press fit 30 bb and bbright systems to reduce the axle width to 24mmthis can be used with rotor 3d amp agilis cranks for use with bbright 46mm systems to convert down to 24mm axle systems this can be used with cervelo bbright frames for rotor 3d amp agilis cranks material constructed of cnc machined 7075 aluminum bearings steel outer bb shell diameter 46mm spindle 24mm