Chord sequence
B♭7 E♭7 A♭7 D♭7 Cmaj7
In every key
Four-note rootless voicings in their two forms, with the 3rd or the 7th on the bottom, played over the root.
Heard in C major
Over Bb7 · V7/♭III
Mode 4 of Melodic Minor
Over Eb7 · V7/♭VI
Over Ab7 · V7/♭II
Over Db7 · subV7
Over Cmaj7 · Imaj7
The major scale and its modes are the most commonly used scales in western music.