Holton French Horn Mouthpiece VDC Rim Inner Diameter: 16.71mm Throat: 5.23mm Depth: Very Deep V-Cup Very Thin Rim I felt this mouthpiece produced surprisingly rich and delicate tones. The throat is wide and the depth is significant, but the inner diameter is small, so it doesn't feel tight. Instead, it gives the impression of producing a really pleasant sound with effortless playing.