Yamaha French horn mouthpiece, model 34C4. Used for about 3 months, and I think it's in good condition because I was using it with other mouthpieces. ⭐︎I'm happy with my embouchure correction, so I'm having a solo sale. From January 15th to 18th⭐︎ - Model: 34C4 - Inner diameter: 17.88 - Bore: 3.98 The following is quoted from the Yamaha website: This model has a larger inner diameter than the 33C4, allowing for even greater volume. The U-cup allows for powerful playing.