These models incorporate the full chromatic scale and allow the player to play in any key using one harmonica. Chromatic models provide the complete 12 note octave with all sharps and flats. Each hole contains four reeds: two are for natural notes and two for chromatic notes.

The reeds for chromatic notes are brought into operation by pushing a slide button on the side of the harmonica. This closes off the air flow from one set of reeds and permits the other set to vibrate freely. The preferred instrument for Jazz and Classical, chromatic harmonicas are also used for Blues and Popular Music.