AKA: Bb9 sus4, Bb ninth suspended fourth, Bb9sus, Bb nine suspended, Bb Dominant ninth suspended 4
A ninth suspended fourth chord is the best option available on the Stradella system to play a suspended chord.
It’s very similar to a ninth eleventh chord but it does not have either the 3rd nor the 5th and the 11th is seen as a 4th.
B♭, E♭, A♭, C
R, 4°, m7°, 9°
B♭ + A♭M
(A# + G#M)
2 + 4
3 + 5