Root on A string
x-10-11-10-12-x
G7♭5 is the G dominant 7 flat 5 chord. Its notes are G, B, D♭ and F. A four-note altered dominant. Mute both outer strings.
x-10-11-10-12-x
Numbers show frets from the low E string to the high e string; x means don't play that string.
Every G, B, D♭ and F on the first 12 frets. The filled dots are the root, G. Build your own shape from any nearby group.
Other G chords
Other dominant 7 flat 5 chords