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.

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.