Austin Custom Brass 1.25CS trumpet mouthpiece, standard series, outer rim diameter Ø 27,13mm (1.068"), inner rim diameter Ø 17,04mm (0.671"), cup shape: Medium C Bowl, relative cup depth: 6, backbore shape: MO, silver plated, closest equivalent: Monette B2S3, ACB 1-1/4 or MV 1-1/4C