Bb Quartal (So What), 1st inversion (D# in the bass)
Also written as Bb quartal/D#.
Notes, from the bass up
D# (bass)G#B#E#A#
The same notes as Bb Quartal (So What) (D#, G#, B#, E# and A#), rearranged so D# is the lowest note. Use it to move between chords with smaller jumps across the keyboard.