In Stock. 45 Day Lowest Price - 100% Satisfaction Guarantee. Bach mouthpiece extensions allow the player to tweak the tuning of the instrument a bit by moving the mouthpiece further out in the receiver. Available for trumpet and tenor trombone. Mouthpiece adaptors allow cornet mouthpieces to be used on trumpets; French horn mouthpieces on Mellophones; tenor trombone mouthpieces on bass trombones; and tenor trombone mouthpieces on European euphoniums (medium shank). This allows the player to stay on the same mouthpiece when changing horns.