Today's bass trombones, besides having a larger bore than the tenor trombone, usually include versatile 'trigger' valves and extended tubing allowing the instrument to play chromatic passages in the lower extremes of its range.
Here at Yamaha Music London, all the Yamaha bass trombones feature the 'F' attachment as standard, such as the 'entry-level' YBL-421GE, with other professional and Custom Series models offering combined 'Eb' and 'D' attachments as well as a 'Gb' attachment on the YBL-830 model and the Gold-brass bell equivalent, the YBL-830G.
Mouthpieces and other accessories
If you're looking for trombone mouthpieces and other accessories, click here...