Comes from British Standard Cycle.English threading on road bikes means a 68mm wide, 34mm internal diameter shell with reverse threading on the drive side.It is the most common threaded standard used today.This kit works with 24mm diameter thru-axle cranks, found from Shimano, FSA, Rotor, and others.Choose between two bearings for the cups.Standard bearings have low resistance thanks to hardened steel races and our ceramic balls.Coated bearings have those same balls installed in ceramic-coated races.Hardened steel for longer life and less rolling resistance.