These 9.98mm outside diameter adapter bushings help you retrofit Kluson tuners in a headstock drilled for larger, die cast tuners. If you are retrofitting a vintage instrument that has been modified or are putting a vintage-style tuning machine onto a modern instrument, you may need these adapter bushings to convert a larger size peg hole to a vintage size to allow for proper fit and function. Use these Kluson adapter bushings with Kluson"s 6 In-Line Vintage Tuning Machines or Kluson"s 3-Per-Side Tuning Machines.Outside diameter: 9.98mmInside diameter: 5.98mm