The G-flat dominant seventh flat five chord (abbreviated "Gb7(b5) chord") is a four-note chord consisting of the notes G♭, B♭, D♭♭, and F♭. The chord is formed by lowering the fifth of a G-flat dominant seventh chord a half step.
G-flat dominant seventh flat five chord
G♭ B♭ D♭♭ F♭
1 3 ♭5 ♭7
tetrad (four-note chord)