Review (4/5): Can be trimmed to fit your face better.
I was able to cut the bottom half off because the bottom would rub on my chin when talking. I use it with a surgeon mask that has the folds in it to attach the silicone piece to. It comes out of the pleat a lot but is workable and doesn't make the sides of the mask open too much as I worried it might. The piece down the nose does leave a red mark on my nose though so thankfully I don't have to wear it for a long period of time.