 The five-valve euphonium (noncompensating) is an extremely rare variation of the euphonium manufactured in the late 19th and early 20th centuries by Britain's Besson musical instrument company and Highams of Manchester Musical Instrument Company.Higham and Besson's "Clearbore" five-valve euphonium was economical but not widely used.The Besson five-valve euphonium featured the standard three piston valves horizontally on top, but had an additional two piston valves off to the side.