Bb major 13th chord
Bbmaj13 chord for piano with keyboard diagram.
Explanation: The B flat major thirteenth is a six-note chord (the 11th, Eb in the case of Bbmaj13, is normally excluded). For practical reasons the chord is normally played with omitted notes and/or inverted. It is often abbreviated as Bbmaj13 (not to be confused with Bb13).
Theory: The Bb major thirteenth chord is constructed by extending the major eleventh chord with a major thirteenth note.
Notes: Bb - D - F - A - C - G