I bought this because I had a metal allergy to my mouthpiece. This covers most but not all of the rim surface so helps, but didn't fully solve the problem. I still had to get a new mouthpiece. However, as a beginner, it helps with comfort and support when I get tired. And I think it does stop prevent some irritation from the metal. It doesn't alter the tone as far as I can tell and fits most of my mouthpieces. The better fit is on the standard wick shape, but I've also used it on a more rounded Yamaha cup and currently with an Alliance 3A. Overall, I'm happy it improves my playing sufficiently to keep using it.