While these do work, they do not fit tightly enough to stay in place and end up falling out constantly. I'm not sure why any of the companies that make these can't make them with some type of 'fins' or 'ribs' around the edges to allow them the compress and hold them in place better. Every type I've ever ordered, including these, are designed the same way and are always a bit too small. I've tried gluing them, adding a small piece of electrical tape, etc. and nothing really works that well.
I give these 3 stars because they can be made to work, but would be 5 if they stayed in place better. If someone can figure that out we'd have a winner!