In 1927, John Dopyera and George Beauchamp formed the National String Instrument Corporation to manufacture resonator guitars under the brand name National. The first models were metal-bodied, and featured three conical aluminum resonators joined by a T-shaped aluminum bar that supported the bridge—a system called the tricone. National originally produced wooden-bodied tricone models at their factory in Los Angeles, California. They call these models the "Triolian", but only made 12. They changed the bodies meant for tricones to single cone models, but kept the name.