Genuine Vincent Bach are the favorite and most widely preferred mouthpieces in the world.  Designed to specifically meet every conceivable playing need possible, Bach has been anticipating the needs of musicians for decades.  The 3515GCP is gold plated with a cup size of 5C, medium depth, and a 16.25mm cup.  As with all Vincent Bach mouthpieces volume and excellent intonation, ease of response in all registers, rich, uniform timbre throughout all ranges, and increasing the player s endurance are all are top priority for all mouthpieces.  This explains why many professional musicians choose Bach mouthpieces.