This is a Yamaha French horn mouthpiece, model 30C4. This mouthpiece features an enlarged throat diameter, gold plating, and DCT treatment. The enlarged throat diameter improves airflow and increases the fullness of the sound. It appears to be in excellent condition with minimal signs of use, possibly due to the low number of times it has been used after gold plating. Please refer to the photos for details. 【Product Details】 Yamaha Horn Mouthpiece HR-30C4 This mouthpiece has a medium inner rim diameter and a U-cup, which produces a sound with a sense of speed. It has moderate resistance and a powerful, rich sound, making it a standard choice. Inner Rim Diameter (mm): 17.28 Throat Diameter (mm): 3.98 → 4.08 Rim Width (mm): 3.66 Depth: Standard Cup Shape: U Other: Gold plating, DCT treatment