The mellophone is a three-valved brass instrument in the key of F or Eb that is used in marching bands and drum and bugle corps in place of French horns. These instruments are used instead because their bells face forward instead of to the back (or to the side), as dissipation of the sound becomes a concern in the open-air environment of marching. Tuning is done solely by adjusting the piping, instead of adjusting both piping and hand position as on the horn.