F# 13sus4, 2nd inversion (C# in the bass)
Also written as F#13sus4/C#.
Notes, from the bass up
C# (bass)EG#D#F#B
The same notes as F# 13sus4 (C#, E, G#, D#, F# and B), rearranged so C# is the lowest note. Use it to move between chords with smaller jumps across the keyboard.