The cornets are the instruments that usually carry the tune in brass bands. Cornets come in various sizes. Pitch depends on the length of tubing in the instrument. The smaller the instrument, the higher its pitch. The pitch of a cornet is determined by the note it plays when no valves are pressed down.
Valves allow the player to change the pitch.
One flugelhorn to a brass band is the rule. The flugelhorn is in the same family as a trumpet and cornet. However, the tubing on a flugelhorn expands in size more rapidly than a cornet's and the resulting tone is considered a bridge between the cornets and the lower-pitched instruments in the band. Because the pitch of a trombone is changed by a slide rather than valves, the tubing is the same diameter, in contrast to other instruments in the brass band that have conical tubing that gradually enlarges from the mouthpiece to the flared bell. The tubing on the trombone gives it a different tone from the mellow one produced by conical instruments.