Trombone
A trombone was a musical instrument from the planet Earth. A member of the brass family, it wais characterized by a slide with which the player varied the length of the tube in order to change pitches. It was commonly used in jazz music. 

Commander William T. Riker was a proficient trombonist, and his trombone was one of his prized possessions. In 2369, Will gave it to his duplicate Thomas Riker as a gift. However, by the next year, Will was in possession of another trombone, a King Instruments model 3B, a classic and well-regarded jazz trombone. ()

In an alternate quantum reality visited by Worf in 2370, Riker was the Captain of the  and his trombone was on display in his ready room. ()

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de:Posaune
Earth musical instruments