This is an auction for a Denis Wick mouthpiece, known for its powerful sound and rich volume. The 4AY is particularly well-suited for Yamaha euphoniums, but I used it on trombone when playing 3rd parts or when I wanted a sound similar to a large-bore trombone. The gold plating feels good on the mouth, and the sound is smooth and powerful, making it a very well-made mouthpiece.