Pros:
Cheap. Though this is not part of the instructions, it is adjustable by bending it over your knee to precise the shape /curve you want. Buy the highest model and shape it yourself.
Cons:
The rubber feet could be of softer material so they slip on the edges less easily, but this is not a huge problem unless you're trying to place it on the ribs where it is obviously likely to slip around the curve of the bout.
Other:
I've used these shoulder rests for decades and they've fallen off only twice. I've replaced them perhaps three times in 40 years. IMO there is nothing wrong with these shoulder rests. I look at modern, expensive shoulder rests and think that the equivalent has already been available for 40 years.
