I am liking it so far. I have been using it for about a week. I am able to control my violin much better because I am getting a better, more comfortable "grip" at my jaw, and the metal is all covered. I think this is actually contributing to my improvement in my playing. My set-up is much more to my liking. Today's practice and playing was greatly improved and I was much more comfortable. My intonation was greatly improved. My violin stayed in the proper position without me having to fight with it. I had no jaw or neck strain the entire time, or after. If it hadn't been for other things, I would have played longer.
It, supposedly, is held to your violin by Velcro. There is a piece of Velcro attached to the underside of the pad, and you are given the opposite side of the Velcro with adhesive on the one side to attach to your chinrest. Then you connect the two.
The reason I said, "... supposedly, is held ..." is because I am not using it. I did not want an issue removing the piece of Velcro that is attached via adhesive to my chinrest. I do not know if there would be, but I did not want to risk it, unless I had to. Well, I just place my Sattler Strad Pad on my chinrest and it does not move or slip. It works great for me that way. It might be different for someone who is active when playing. The Velcro is still attached to the underside, I just do not use it.
With it just sitting on top of the chinrest, I don't have to put Velcro on the chinrests of my other violins or violas. I can just set the pad on whatever instrument I want to play. Yes, the large is large enough for my viola chinrest.
I say that I place it on top of my chinrest, but there is a flap that covers the end of the instrument so the pin and hardware are cushioned. It is wonderfully comfortable.
Now, there is a slight odor to it when it is new, as there is with most manmade materials. It has dissipated greatly and has only a slight aroma remaining, which will dissipate soon. It is very soft and flexible.
It is washable. However, I have read where someone complained the soap would not come out. I would not have used soap, or at least not directly on it. I would just wipe it down with a lint free soft cloth with hot water on it and then let it air dry. Again, I don't play with a lot of activity and get all sweaty. But, take heed of the soap, or supposed, soap issue. It was just mentioned on a site I was on when getting info.
I know some will say it is too expensive. It depends on your circumstances and what you are willing to spend to make your instrument more comfortable. It is relative to you and your desires. It may not be for everyone, but, so far, it has solved my issue.