A chromatic button accordion is a type of button accordion where the melody-side keyboard consists of rows of buttons arranged chromatically. The bass-side keyboard is usually the Stradella system or one of the various free-bass systems. Included among chromatic button accordions are the Russian bayan and Schrammel accordion. There can be 3 to 5 rows of vertical treble buttons. In a 5 row chromatic, two additional rows repeat the first 2 rows to facilitate options in fingering.
Chromatic button system (type C)
Chromatic button system (type B)
Comparing the layout to the piano accordion, the advantages of a chromatic button accordion are the greater range and better fingering options.[notes 1] On the other hand, some fingering positions require twisting of the wrist and the aspect of alternative fingering patterns may stunt one in sessions of difficult sight reading.
Throughout the former Yugoslavia a 6-row chromatic button layout is used based on the B system. It is referred to as dugmetara.