Kluson? 3 Per Side Deluxe Series Tuning MachinesThis complete Kluson? set of 3 per side tuning machines is available with oval or keystone buttons and a high quality gold or nickel plating with an improved 15:1 gear ratio for more stable and accurate tuning. The housing and button type are period correct for a variety of production dates. This set comes complete with both bass and treble side tuning machines, 8.8mm O.D. vintage bushings with 1/4 inch I.D. and mounting screws needed for installation. Uses Kluson Bushings MB65N US (Nickel) or MB65N US (Gold) Outside diameter = 8.85mm Inside diameter = 1/4 inch or 6.48mm