The chromatic accordion is a very versatile instrument. The right hand operates a piano or button keyboard and can be played in all keys like the piano. The left hand operates the buttons of the standard bass.
The standard bass is split into bass-and chord-rows. The playing of the right hand resembles the style of accompaniment traditionally given by a bass or rhythm guitar. Therefore the chromatic accordion player has actually three instruments available: a melodic instrument (right hand), a bass and a harmonic accompaniment (left hand) - and this for all the pitches and Keys.