01-DW5880E-SM3.5M, DENIS WICK STEPHEN MEAD EUPHONIUM MOUTHPIECE, SILVER PLATED, MEDIUM SHANK, 3.5M

Slightly larger cup and throat than the SM3 for an open sound.
Cup diameter: 26.40mm.
Rim width: 6.80mm.
Throat: 7.62mm.
Backbore: Barrel. Medium shank.