The trumpet mouthpieces of the GP series from Yamaha are characterized by a centered and full sound. The gold-plated bowl and rim rest warmly and comfortably on the lips. The additional weight of the mouthpiece makes the tones hit the center better and the sound fuller. The medium-flat bowl makes it easier to play in the high register without having to do without a full sound. The GP 14B4 from Yamaha has an inner diameter of 16.46 mm and a bore of 3.65 mm.