I 've noticed how this type of dampeners is very popular among many of us. I love them too and I am "stuck" with them, after having tried many other dampeners. I like how they : 1. Dampen both vibrations and noise 2. Don't "impose" on the character of the strings 3. They are "neutral looking" Major cons : 1. Maybe not suitable for not dense patterns, or at least not so stable Feel free to add your remarks and share your experience about this sort of dampeners. Suggestions, reviews, comparisons are welcomed !! Personal experience : I mainly use the Unique Sampras ones and I have a nice stock of them. Many argue that there is a difference between red and black. Really don't know... I dare to say that black ones might be a little softer (?) Generally speaking, I think these are the benchmark for most of us. The ones from Babolat are a bit stiffer, not bad at all, tend to pop out a bit more easily though. Custom damp dampeners also give you the option to have a dampener with more mass if you add a silicone part that is included in the package, but then again it won't be an "O" ring dampener any longer. I put them on my Babolat PST Ltd., they look great. I 've found and recently playtested "O" ring dampeners from Pacific. They come in white, black and light orange. Noticeably bigger, a little heavier, more stable for 16x19 and 16x18 string patterns. Unfortunately they have a quite large rim gap to host the string, which does not provide ideal noise dampening. Larger gauge strings exclusively (?) Lastly, I have tried "O" ring dampeners from Topspin. Very similar to Unique dampeners. Same size, they come in white, black and red (rare to find) and they are a bit softer. A plus point is that they have approximately 25 % more mass than the Unique Pete Sampras ones, which will theoretically give them more dampening power. IMO they feel very similar overall, I think that some can end up prefering them over the ones offered by Unique (which remain the benchmark). Have in mind that it 's difficult to find them in the U.S.A.