Six-Sided Harmonica.

From the website:

Made by the renowned Hohner instrument company founded in Germany in 1857 and manfucturer of harmonicas used by such Blues luminaries as Howlin Wolf, Little Walter, and Junior Wells, this unique musical instrument, which has been in continuous production since before 1900, combines six harmonicas into a single component, creating the largest tonal range available in any Hohner tremolo model. Tremolo harmonicas employ two reeds per note, and each harmonica on this instrument has 24 double holes for a total of 48 reeds per harmonica that produce a warm vibrato characteristic of the world-famous Hohner sound.

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