Gb11 chord

The G-flat dominant eleventh chord (abbreviated Gb11 chord) is a six-note chord consisting of the notes G♭, B♭, D♭, F♭, A♭, and C♭. The chord is formed by adding an eleventh to the G-flat dominant ninth chord.

In practice, the third (B♭) and fifth (D♭) are often omitted from the Gb11 chord to avoid a very dissonant sound, and because it's not always possible to play all notes simultaneously.