Used on literally hundreds of Martin guitars of that era.
Components of 1950s-60s American-made Grover Imperial tuning machines.
American-made, nickel-plated Grover Rotomatic tuners in the box.
American made, 6-on-a-side.
An extremely rare four-piece set.
For all intents and purposes these are 1930s Grover G-98 tuners.
