Austin Custom Brass 3DS trumpet mouthpiece, standard series, outer rim diameter Ø 27,08mm (1.066"), inner rim diameter Ø 16,51mm (0.65"), cup shape: Medium Shallow Bowl, relative cup depth: 4.5, backbore shape: A2, silver plated, closest equivalent: Monette BLM, GR 65MS/S or Pickett 5D