The D flat suspended fourth chord is a 3-note chord consisting of the notes Db, Gb and Ab.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Dbsus4.
Chords that are a superset of Dbsus4. The chords include more notes but always Db, Gb and Ab.
Chords that are a subset of Dbsus4. These contain less notes but all of them are included in Dbsus4.
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 Dbsus4 chord. Feel free to save or share the image as needed.