Schilke 19 vs Schilke M1D
The Schilke M1D has a wider cup diameter, the Schilke M1D has a larger throat opening.
Cup Diameter
The Schilke M1D has a cup diameter of 17.71 mm / 0.6972 in compared to 17.65 mm / 0.6949 in on the Schilke 19 — a difference of 0.06 mm / 0.0024 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a medium cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Schilke M1D has a wider throat (3.86 mm / 0.1520 in vs 3.65 mm / 0.1437 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.