Cb13 chord

The C-flat dominant thirteenth chord (abbreviated Cb13 chord) is a seven-note chord consisting of the notes C♭, E♭, G♭, B♭♭, D♭, F♭, and A♭. The chord is formed by adding a thirteenth to the C-flat dominant eleventh chord.

In practice, the fifth (G♭) and eleventh (F♭) are often omitted from the Cb13 chord to avoid a very dissonant sound, and because it's not always possible to play all notes simultaneously.