What does the K622 on the clarinet mean, with the logo, referring to Mozart's K622 in A Major, representing the order of Mozart, marked by K. or K.V.. "Clarinet Concerto in A Major" (K622) is the most beautiful of Mozart's twenty and the only clarinet compositions, called "autumn" music with a hint of sadness in beauty. Lower B tuning clarinet, invented in the early 18th century, is today the standard orchestral playing clarinet. Lower B tone generally refers to the lower B tone clarinet, which refers to the actual low second tone when the score is the C tone.