The FSA Mega Exo ATB BB is the bottom bracket that is designed to work with all of FSA's thru-axle style MTB cranksets. Two cups are attached to a sleeve, with the cups outside the bottom bracket with the sleeve inside. The sealed unit runs on two 25x37x7mm sealed ball bearing cartridges. The bearings and the races are steel. The package includes all of the above and dust covers. 134g.