Classical. Popular set of Mozart duets here set for two trombones. Trombone 1 is in tenor clef throughout. The second part can be played by either a tenor or bass trombone. Published in score form. Mr. Sauer has transposed these duets from their originalkeys to better fit the tessitura of the trombone, numbers 1-4 are in F, 5-8 are in G and 9-12 are in A.