JK 02AK Bass Trombone Mouthpiece Cup Diameter: 29.0mm Depth: AK (Deepest for bass trombone) ★Used item, purchased and test-played a few times. This mouthpiece has a large diameter among European-made mouthpieces, and is a good match for European instruments. It has a lightweight body, but is still powerful and easy to use. This model is rare in Japan, so please take this opportunity to try it.