Warburton Trumpet Mouthpiece Backbore*This product might have been tried before in our store. If you want us to order you a brand new backbore (or any mouthpiece related item) write to us ! 4, 5, 6 Tight to medium. With progressively less resistance, these models produce a bright and very projecting tone. The #5 is by far our most popular with strong lead players. 7, 8, 9 Medium large sizes. The #7 has been the best selling model because it provides a good balance of sound quality