Austin Custom Brass 1-1/4C trumpet mouthpiece, standard series, outer rim diameter Ø 27,18mm (1.07"), inner rim diameter Ø 17,07mm (0.672"), cup shape: Medium Deep C, relative cup depth: 7, backbore shape: MO, silver plated, closest equivalent: Bach 1-1/4C, Tilz 1-1/4CE or Monette B2