2½-row diatonic button accordion

Club-Model Accordions and 2&frac12;-row button accordions are two-row accordions with a partial third (inner) row that contains useful accidentals. The club accordion is usually tuned in C/F, or sometimes Bb/Eb, and includes a "gleichtone" button which plays the same note on both press and draw. Not all 2 1/2 row button accordions are "Club Accordions."