flügelhorn (flü`gəlhôrn'), three-valved brass instrument similar in size and shape to the trumpet trumpet, brass wind musical instrument of part cylindrical, part conical bore, in the shape of a flattened loop and having three piston valves to regulate the pitch.
..... Click the link for more information. but having a conical rather than a cylindrical bore and possessing a larger bell. Because of these differences the tone of the flügelhorn is mellower than that of the trumpet. It is used traditionally in concert bands and has recently been used in jazz ensembles.

flügelhorn

Brass musical instrument, a valved bugle. It has three valves and a wider bore than the cornet and is usually pitched in B-flat. The flügelhorn was invented in Austria in the 1830s. It has maintained its identity—particularly its bore and its squat shape—better than has the formerly very similar cornet. Long used in European military bands, it is now also used in jazz and popular music.