These Kluson steel replacement adapter bushings are intended for use in converting a modern 10mm drilled headstock to accept a vintage Kluson stamped steel tuning machines with the original US 1/4 inch string post diameter. Many repair shops use these to convert a vintage instrument back to original peg head specs.
Outside diameter = 9.98mm.
Inside diameter = 1/4 inch or 6.35mm
Set of 6
*These are factory parts. Instructions are not included. If you have any doubt about installation, consult your local luthier.