Kanstul 1690 contra-bass-trombone, key: F, inline, dual bore: .562 " - .593 ", brass bell, bell diameter: 10 1/2 ", nickelsilver outer slide, with Kanstul Controlled Resistance valves: F/C/Db/A (bore: .620 " and .655 ", hand support is fully adjustable for improved balance, lacquered, without case