C# Half Diminished chord (C#m7b5) on the guitar fretboard

The C# Half Diminished chord (C#m7b5) is made of C# (the root), E (minor third), G (diminished fifth) and B (minor seventh). The fretboard shows every one of them across the neck in standard tuning (E A D G B E), and plays them back so you can hear the chord.

The half diminished chord is a diminished triad with a minor seventh, so it keeps the flat five of the diminished chord but not its seventh. It shares its notes with a minor sixth chord built a minor third higher, so the two shapes overlap on the neck. It sits between the minor seventh and the diminished seventh.