SRX ISIS CNC machined, heat treated, hollow chromoly M15 spindle. Shot peened finish for fatigue strength. Forged CNC'd aluminum cups reinforcing sleeve. Single row, full-ball, sealed cartridge bearings. Low friction labyrinth spindle seal keeps out contaminants increases bearing life. Newly improved extreme conditions bearing grease. 64 ball bearings in each bottom bracket. Fixed cup spacer 2.5mm allows BB to be used with either 68 or 73mm shells. Fixed cup on drive side. Proprietary non-side loading design. NC machined, heat treated, hollow CrMo M15 spindle Proprietary non-side loading design Fixed cup on drive side Fixed cup spacer 2.5 mm allows BB to be used with either 68 or 73 mm shells 4 ball bearings in each bottom bracket