Bicycle Headset Fork Crown Race for SEALED 1" headset 27.0mm * 27.0mm inner diameter * These are designed specifically for the Neco H671 and H671A SEALED CARTRIDGE BEARING headset that we sell. Notice the "ramped" design - this will not work with loose ball headsets. It might work with other 1" threaded sealed bearing headsets, but only if the bearing has a similar taper to the bearing in the H671. * This size is most often used on road bike and cruiser bike 1" threaded forks. If you have a headset and the crown race just won't go on without excessive force, then you probably have a 26.4mm and need this 27.0mm. SOLD INDIVIDUALLY