the brass section has four sections: trumpet, trombone, french horn, and tuba. some of these come in several sizes. the article on transposing instruments explains more about it. the trumpet may have several slightly different sizes. the lowest kind is a bass trumpet. the trombone may be an alto, tenor, bass or contrabass trombone. the french horn, like the other brass instruments, has changed over the years. modern horns have at least three valves and are usually in f. they often sit in a different place to the other brass. the tuba comes in different sizes and the player or conductor must decide which to use for the piece they are playing. there are large ones called contrabass tubas. a small tuba is commonly also seen and is called a euphonium or a baritone horn.