Yamaha 14F4 GP Series Flugelhorn MouthpieceA brass instrument mouthpiece is much more than an add on or accessory. It is a vital part of your instrument. As interface between artist and instrument, it can mean the difference between mediocrity and mastery. The GP Series has been created especially for professionals who require superior quality from their mouthpiece. The GP Series features an innovative shape and extra heavy gold plate finish for players who prefer a focused, concentrated tonal