As fitted to a variety of electric guitars produced at the Matsumoku guitar factory, Matsumoto Japan from the mid 1970s. Available with gold or chrome plating. The gold-plated version typically appeared on Les Paul Custom style solid body guitars such as the Kimbara N114 / N115 / N116 / N117, whilst chrome-plated tuners were fitted to Gibson Les Paul and SG style guitars branded Arbiter, Eros, Jedson, and most likely numerous others.
These tuning keys are very similar to these metal-buttoned equivalents used from the late 1960s into the 1970s; in fact the plastic button tuners replaced the metal buttoned version for Matsumoku Les Pauls from about 1974.
Tuners are attached to the headstock reverse with two 9.2mm round cross head screws. Post diameter is dead on 6mm, post length is 32mm (1.26"). The headstock hole has an approximate diameter of 8mm. The bolt that holds the post to the cog seems to have an ISO M2.5 thread, with a major diameter of 2.55mm. This is a different thread used in older Matsumoku tuners (which typically used a pre-1967 Japanese M3 thread). Ferules are 6.7mm tall, with an 11.0mm major diameter, 8.4mm minor diameter (grooved), and a 6.2mm internal diameter.
List of Matsumoku tuning keys

Matsumoku closed gear tuner in situ on a 1975 Kimbara N117 - front of headstock view.

Matsumoku closed gear tuner in situ on a 1975 Kimbara N117 - reverse headstock view.

With cover removed.

Headstock front with tuning key removed - the hole has an (approximately) 8mm diameter.

Headstock reverse with tuning key removed - the hole has an (approximately) 8mm diameter.

The underside of each tuning key is marked 'JAPAN'

Matsumoku closed gear tuner with cover removed. Side view. Note how much wear these tuners have sustained with significant plating loss.

The tuning key partially disassembled

The tuning key disassembled to show its constituent parts

Matsumoku closed gear tuner cover detail

Closed gear tuner cover underside - the gold plating is still in great condition inside the tuner's cover

The tuner ferule, top view

Ferule, underside view
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