Yamaha YAMAHA French Horn Mouthpiece HR-32-GP Rim Inner Diameter (mm): 17.48 Throat Diameter (mm): 4.4 Larger rim inner diameter than 31, producing a powerful sound in the low register. Large cup volume, allowing for a calm and rich resonance. There are no noticeable scratches, and it can be used without any problems. I think it's a light and responsive model. My mouthpiece selection (indecision) has settled, so I hope someone will use it. Thank you.