Bach trumpet mouthpieces have been designed in an orderly progression from the largest to the smallest diameters, and from the deepest to the most shallow cup, all with a choice of rim designs. Rim shape is described for each individual model. Model numbers progress numerically from model no. 1 with the largest cup diameter, to model no. 20C with the smallest cup diameter. Cup depths are notated with letters. "A" cups are the deepest; standard cups have no letter designation; progressively shallower cups are marked "B" through "F".

Empty Space Model Cup Depth Approx Cup Dia.  Rim Shape

1

Deep 17.5 mm Medium thin 1X
Deep 17 mm Medium wide 1B Medium deep 17 mm Medium wide 1C Medium 17 mm Medium wide 1D Medium shallow 17 mm
Medium wide
1E Shallow 17 mm Medium wide 1 1/4C Medium  17 mm Medium wide 1 1/2B Medium deep 17 mm Medium wide, not too sharp 1 1/2C Medium  17 mm Medium wide, not too sharp
2 Deep 16.5 mm Medium wide, lowered toward the outside 2C Medium 16.5 mm Medium wide, lowered toward the outside 2 1/2C Medium 16.4 mm Medium wide, lowered toward the outside 2 3/4C Medium 16.4 mm Medium wide, lowered toward the outside. Slightly more narrow than No. 21 ⁄ 2C. 3
Deep 16.3 mm Medium wide 3B
Medium deep 16.3 mm Medium wide 3C Medium 16.3 mm Medium wide 3CW Medium 16.3 mm Slightly wider, lowered to outside 3D Medium shallow 16.3 mm Medium wide 3E Shallow 16.3 mm Medium wide 3F Extra shallow 16.3 mm Medium wide 5A Very deep 16.25 mm Medium wide, rounded inside edge 5B Medium deep 16.25 mm Medium wide, lowered toward the outside. Medium sharp edge 5C Medium 16.25 mm Medium wide, well rounded toward the inside and outside, fairly flat 5MV Medium deep 16.25 mm Medium wide, lowered toward the outside. Medium sharp edge 5SV Shallow 16.25 mm Medium wide, lowered toward the outside. Medium sharp edge 5V Very deep 16.25 mm Medium wide, lowered toward the outside. Medium sharp edge 6 Deep 16.2 mm Medium wide, not too sharp 6B Medium deep 16.2 mm Medium wide, not too sharp 6BM Medium deep 16.2 mm Medium wide, not too sharp 6C Medium 16.2 mm Medium wide, not too sharp, rather flat 7 Deep 16.2 mm Medium wide, lowered toward the outside. Medium sharp inside edge 7A Very deep 16.2 mm Medium wide, lowered toward the outside. Medium sharp inside edge 7B Medium deep 16.2 mm Medium wide, lowered toward the outside. Medium sharp inside edge 7BW Medium deep 16.2 mm Medium wide, lowered toward the outside. Medium sharp inside edge 7C Medium 16.2 mm Medium sharp inside. Well-rounded edge with a perfect grip. 7CW Medium 16.2 mm Slightly wider, gradually lowered toward the outside 7D Medium shallow 16.2 mm Medium wide, lowered toward the outside. 7DW Medium shallow 16.2 mm Slightly wider 7E Shallow 16.2 mm Medium wide 7EW Shallow 16.2 mm Slightly wider 8 Deep 16.2 mm Fairly wide with slightly flatter surface than No. 7. Rounded inner edge 8B Medium deep 16.2 mm Fairly wide with slightly flatter surface than No. 7B. Rounded inner edge 8C Medium 16.2 mm Fairly wide with slightly flatter surface than No. 7C. Rounded inner edge 8 1/2 Deep 16.1 mm Medium wide, lowered toward the outside. Med. sharp inside edge 8 1/2A Very deep 16.1 mm Medium wide with rounded inner edge 8 1/2B Medium deep 16.1 mm Medium wide, lowered toward the outside. Med. sharp inside edge 8 1/2C Medium 16.1 mm Medium wide 8 3/4 Deep 16.1 mm Medium wide, not too sharp 8 3/4C Medium 16.1 mm Medium wide, slightly flat 9 Deep 16.05 mm Medium wide, lowered toward the outside 9A Very deep 16.05 mm Medium wide, well rounded 9B Medium deep 16.05 mm Medium wide, lowered toward the outside 9C Medim 16.05 mm Medium wide, lowered toward the outside 9D Medium shallow 16.05 mm Medium wide, lowered toward the outside 10 Deep 16 mm Fairly wide with rather broad, flat surface 10B Medium deep 16 mm Fairly wide with rather broad, flat surface 10C Medium 16 mm Fairly wide with rather broad, flat surface 10 1/2A Very deep 15.9 mm Medium wide, well rounded 10 1/2C Medium 15.9 mm Medium wide 10 1/2CW Medium 15.9 mm Extra wide, high toward the inner edge 10 1/2D Medium shallow 15.9 mm Medium wide, high toward the inner edge 10 1/2DW Medium shallow 15.9 mm Extra wide, high toward the inner edge 10 1/2E Shallow 15.9 mm Medium wide, high toward the inner edge 10 1/2EW Shallow 15.9 mm Extra wide, high toward the inner edge 10 3/4A Very deep 15.75 mm Medium wide, well rounded 10 3/4CW Medium 15.75 mm Extra wide 10 3/4EW Shallow 15.75 mm Extra wide 11A Very deep 15.7 mm Medium wide, well rounded 11B Medium deep 15.7 mm Medium wide, well rounded 11C Medium 15.7 mm Medium wide 11D Medium shallow 15.7 mm Medium wide, well rounded 11DW Medium shallow 15.7 mm Extra wide 11EW Shallow 15.7 mm Extra wide, high toward the inner edge 11 1/2A Very deep 15.65 mm Medium wide, well rounded 11 1/2C Medium 15.65 mm Medium wide 11 3/4C Medium 15.6 mm Medium wide, well rounded 11 3/4CW Medium 15.6 mm Fairly wide, rather flat, not too sharp 12 Deep 15.2 mm Broad, rather flat. 12B Medium deep 15.2 mm Broad, rather flat. 12C Medium  15.2 mm Broad, rather flat. 12CW Medium  15.2 mm Broad, rather flat toward the inside 17 Deep 15.1 mm Medium wide. 17C Medium 15.1 mm Medium wide. 18 Deep 15.1 mm Broad, rather flat. 18C Medium 15.1 mm Broad, rather flat. 20C Medium 15 mm Medium wide.