Open shape
x0102x
A7♭5 is the A dominant 7 flat 5 chord. Its notes are A, C♯, E♭ and G. A four-note altered dominant. Mute both outer strings.
x0102x
Numbers show frets from the low E string to the high e string; x means don't play that string.
Every A, C♯, E♭ and G on the first 12 frets. The filled dots are the root, A. Build your own shape from any nearby group.
Other A chords
Other dominant 7 flat 5 chords