This is the SRAM/Truvativ Team GXP English Bottom Bracket. Features: Includes two spacers that are only needed for installing a mountain crankset on a 68mm bottom bracket shell; spacers are not needed for road cranks Giga X Pipe (GXP)- An external bearing system with 3D forged, heat treated and CNC'd 24mm OD Chromoly spindle integrated with right crank arm; custom cartridge bearings with eight seals and CNC'd alloy cups Specifications: Frame Interface: BSA/English Threaded Spindle Interface: SRAM/TruVativ GXP Bottom Bracket Shell ID: 1.37 Shell Width: 68mm, 73mm (w/Spacers) Material: Chromoly Color: Grey Weight: 106g