When Josef Klier resumed the production of mouthpieces in Birkenfeld in 1948, the news of this production quickly reached the surrounding bands of the US Army. Up to this time, he had chiefly produced mouthpieces for rotary valve instruments.
But trumpeters and trombonists of the Army bands preferred another cup shape for their instruments. They handed over samples of mouthpieces to Roland Klier, which had been produced in Mount Vernon, New York.
Accurate in every detail, the copies of these models produced by Roland Klier were greeted enthusiastically by the army musicians. As these mouthpieces had their origin in the US, Josef Klier thought it logical to unite the new models under the designation JK USA Line.