Kluson TonePros KBW guitar tuners have the same great tuner improvements as the B3 Series and use the same bolt bushing format. KBW tuning machines were created as the answer for professional guitarists who need to update older Junior and Special guitars which have been modified for the larger hole heavier and bulkier tuners of yesteryear. The KBW tuner's vintage-style white round plastic button on individual 3-on-a-side tuners makes it right at home on older guitars as well a very popular choice for new models from major manufacturers. KBW tuners have the same great technology and quality upgrades as the B3 series, including the very tight 15:1 high tuning ratio. 12/64" shaft size. Now you can retrofit your vintage guitar with no modification.