Unique 3-on-plate tuning machines, with true-to-vintage styling. Martin Guitars specially commissioned Golden Age to create these tuners for their 000-30 Authentic 1919 reissue guitar. Lyre designs adorn the engraved steel baseplates, and the worm gears are mounted in old-style square supports. These tuners also feature the “worm-under-post” reverse gearing popular in the early part of the 20th Century. Golden Age tuners are the rebirth of popular early 20th Century open-gear tuning machine designs. They're ideal for adding an authentic vintage touch to reproduction instruments, while also improving their tuning. Features include: 15:1 gear ratio for improved tuning Vintage-style square riveted worm supports Round mother-of-pearl knobs with vintage retainer screws Worm gear under string post 0.236" (6.00mm) string post diameter Original mounting screw spacing (8 screws included) 1-3/8" (34.93mm) string post spacing Bright nickel finish