2 tubas (or 2 bass trombones) or tuba/bass trombone with downloadable backing tracks (downloads included for both parts 1 and 2) recorded by Zach Collins Concert Duets is a collection of 14 arrangements of works by prominent 18th-century composers, mostly taken from Trio Sonatas. Duet 11 is a Jim Self original work in the Rococo style; and Duets 12, 13 and 14 are arrangements of the three-movements of theBach Concerto for Two Violins. Included with this edition are play-along recorded tracks by tubist Zach Collins, who also served as editor of the current edition.