Root on A string
x1213x
B♭7♭5 is the B♭ dominant 7 flat 5 chord. Its notes are B♭, D, F♭ and A♭. It is the same chord as A♯7♭5. A four-note altered dominant. Mute both outer strings.
x1213x
Numbers show frets from the low E string to the high e string; x means don't play that string.
Every B♭, D, F♭ and A♭ on the first 12 frets. The filled dots are the root, B♭. Build your own shape from any nearby group.
Other B♭ chords
Other dominant 7 flat 5 chords