The D flat altered chord is a 4-note chord consisting of the notes Db, F, Cb and Ebb.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Dbalt7.
Chords that are a superset of Dbalt7. The chords include more notes but always Db, F, Cb and Ebb.
In case you prefer a non-interactive variant of the chord chart, we've embedded a PNG image below that shows the notes for the the Dbalt7 chord. Feel free to save or share the image as needed.