The Wolf Tooth T47 External Bottom Bracket covers road, gravel, and cyclocross frames in 68mm and 73mm shell widths without requiring separate cup sets for each. One adjustable-width sleeve handles the range, and the same AISI 52100 chrome steel bearings with Acosur ZNA coating and multi-layer sealing Wolf Tooth uses across their BSA lineup are machined and assembled at their Minnesota shop. What Our Gearhead(R) Experts Are Saying:"I spec this on builds where the frame is T47 and I want a bottom bracket that won't need to be fought out at the next service. The multi-layer sealing keeps grit out, and the Acosur ZNA-coated bearings stay smooth well past where a cheaper unit starts to crunch."