The S-B and M-B cups are modified cups for those whose lips touch the bottom. GR emphasizes the part called the alpha angle, and the -B cups have a lower alpha angle than the original. In Japanese terminology, a low alpha angle is roughly equivalent to having a "scoop." The 65M-B has a lower alpha angle than the 65M, but the cup volume is the same as the 65M by adjusting the volume in the shoulder area from the bottom of the cup to the throat. The inner rim diameter is between Bach 3-5, and is similar to a C-D cup. This model can be used flexibly in both brass band and pop music. Compared to the M cup, the shoulder is more upright, so the response is faster and the tone is slightly brighter. It is becoming difficult to obtain new ones in Japan, so how about taking this opportunity? By the way, GR has not stopped production! They recently purchased new brass round bars, so although they are not in a position to increase production, you can still obtain one by placing a personal order, although it will take time.