Promax EX-1 External Bottom Brackets feature cold-forged and CNC-machined alloy cups, dual-labyrinth bearing covers and precision sealed bearings. They are the perfect match to Promax CF-2 and HF-2 cranks and ultimate upgrade to the budget bottom brackets sold with most cranksets. Specifications: Frame Interface: BSA/English Threaded Spindle Interface: 24mm (Shimano Hollowtech II, FSA MegaExo, Surly OD, FSA MegaExo Light, RaceFace EXI) Bottom Bracket Shell ID: 1.37 Shell Width: 68mm, 73mm Color: Black Weight: 103g