The Chromatic Harmonica - The Musical Harmonica.
The chromatic is mostly used for jazz, classical, and pop music- The chromatic harmonica is typically used in jazz, classical, pop, and music where the melodies require more than a 7-note scale (like the one on a standard diatonic). A classic example of where a chromatic would be required is the theme song to "Midnight Cowboy". The original theme to "Sesame Street" was also played on a chromatic.
With a Chromatic Harmonica, all accidental notes (sharps and flats) are immediately available by pushing in the slide button. Each single hole contains four reeds; two natural tones and two chromatic tones are enabled by pushing in the slide button on the side of the harp. Most chromatics are solo tuned, meaning each group of 4 holes completes one octave (inhale for one note, exhale for another). The slide button adds the "black keys" of the piano, by changing the full tones to half steps.