Breather filter material

[forestb]

I have a breather on my valve cover that you can take apart. Inside there is a filter material that looks a lot like the material that is inside a fuel cell that keeps the gas from sloshing around. It is starting to fall apart. I there something that I can replace it with. It is shaped like a donut but it doesn’t have anything that goes through the canter. It is inside an empty cavity.