ToKo Klangbogen Brass 24K GP

This, unbelievably, works well. It seems to minimise the airflow vibration disruption around the neck (I think!) . But is noticeable is that the tone is clearer and the high and low notes pop out more easily. What it also does is minimise the overtones across the whole range. Now this is something you might not like. If you want easier to get notes this is good. If you want a dirty sound, not so good.