It's a 10-String Extended Range Classical Guitar.
According to Wikipedia: "The extended-range classical guitare is a classical guitare with additional strings, normally extra basse, bass strings past the basse, bass E string, that are available on the fingerboard.
Many configurations have been produced, but the ten-string classical guitare received a particular boost in 1964, when Narciso Yepes performed the Concierto de Aranjuez with the Berlin Philharmonic Orchestra, using a ten-string guitare developed for him par José Ramírez III and a specific tuning designed to balance all resonances of the chromatic scale."
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