The E flat major seventh chord is a 4-note chord consisting of the notes Eb, G, Bb and D.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Ebmaj7.
Chords that are a superset of Ebmaj7. The chords include more notes but always Eb, G, Bb and D.
Chords that are a subset of Ebmaj7. These contain less notes but all of them are included in Ebmaj7.
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 Ebmaj7 chord. Feel free to save or share the image as needed.