Gb13 chord

The G-flat dominant thirteenth chord (abbreviated Gb13 chord) is a seven-note chord consisting of the notes G♭, B♭, D♭, F♭, A♭, C♭, and E♭. The chord is formed by adding a thirteenth to the G-flat dominant eleventh chord.

In practice, the fifth (D♭) and eleventh (C♭) are often omitted from the Gb13 chord to avoid a very dissonant sound, and because it's not always possible to play all notes simultaneously.