Bruno Tilz 211-513 M vs Yamaha HR-31D4
The Yamaha HR-31D4 has a wider cup diameter, the Bruno Tilz 211-513 M has a larger throat opening.
Cup Diameter
The Yamaha HR-31D4 has a cup diameter of 17.28 mm / 0.6803 in compared to 17.00 mm / 0.6693 in on the Bruno Tilz 211-513 M — a difference of 0.28 mm / 0.0110 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a deep cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Bruno Tilz 211-513 M has a wider throat (4.80 mm / 0.1890 in vs 4.50 mm / 0.1772 in). A wider throat allows more air through, increasing volume and projection but reducing resistance.
Which is better?
Neither mouthpiece clearly dominates the other — the right choice depends on your embouchure, playing style, and the sound you're after. Try both if possible.