Electro-Harmonix Voice Box Harmony Machine and Vocoder Intelligent vocal harmonies: follows the chords you play on your instrument and the note you sing to create from 2 to 4 part harmonies in the same key as your instrument Natural Glissando: harmony notes will follow your natural glissando between notes without interval stepping Vocoder mode Very professional quality pitch shifting algorithm produces realistic harmonies US96DC-200BI power supply included Intelligent vocal harmonies: follows the chords you play on your instrument and the note you sing to create from 2 to 4 part harmonies Natural Glissando: harmony notes will follow your natural glissando between notes without interval stepping Vocoder mode Very professional quality pitch shifting algorithm produces realistic harmonies US96DC-200BI power supply included