The 1539M15 is a Hammond Organ model which was produced between 1959 and 1964. It is a two-manual, three-keyboard instrument, with one 44-note keyboard controlling the lower manual and two 44-note keyboards controlling the upper manual. The instrument also has 36 pedals and a twelve-drawbar tone generator. The 1539M15 also includes vibrato, percussion, and key-click effects, as well as the reverberation of the Leslie speaker. As with other Hammond organs, the 1539M15 features rotating speakers, chord and bass pedals, as well as pre-set orchestral voices.