Kelly 31 vs Schilke 29
the Kelly 31 features a deeper cup, the Kelly 31 has a larger throat opening.
Cup Diameter
Both mouthpieces have virtually identical cup diameters at 17.53 mm.
Cup Depth
The Kelly 31 has a — cup while the Schilke 29 has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Kelly 31 has a wider throat (3.80 mm vs 3.60 mm). A wider throat allows more air through, increasing volume and projection but reducing resistance.
Material
The Kelly 31 is described as Lexan polycarbonate, and the Schilke 29 as unspecified. Material affects mass, warmth, and how quickly the piece responds.
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.