there is no such thing as a "glass" mouthpiece. There are clear plastic mouthpieces, which I have seen made by all sorts of companies (including selmer usa, but for clar.) - mostly for students...showy pieces. The pro ones are made out of crystal - crystal is a lot more durable, harder and harder to crack. additionally, crystal can't shatter. Your better watches have crystal..."windows" My fossils, relics and citizens all have harde lives of recreational vehicle trips, oil changes and so on - I have never so much as scratched one yet. the material a mouthpiece is made of, affects the tone little at all. the design is over 98 percent of the piece. (unless you were to try say, make one out of styrofoam.) Nothign is going to chip off in your mouth while playing a crystal mouthpiece - I used to have a couple brilhart tonalites - they were my main jazz pieces for a while and they never did anything adverse. hell, I even dropped them, on average I would say once every 5 days and nothing happened. I have a clarinetist friend who has a pomarico mouthpiece that he has dropped numerous times - it has a crack in it, but it is only cosmetic. If you do play it though, I would recomend having your tech band the shank, much the same way bake a lite, wood and earlier rubber pieces were. (actually many rubber pieces are still banded, but you just can't tell - the thing on the soloist is structural, the s-80 is REALLY thick at the beginning of the shank etc.) just to strengthen the shank a bit. hell, I have that done to all of my more valuable pieces.