I know others have complained about this item, but I think it's MORE useful than the plastic mat things. Those don't even last one project, then, into the landfill goes MORE plastic, something that should end.The mat is filled with a heavy compression of felt itself, I believe. The surface does pick up some of the wool you're using, but it's very small, and came out easily.It's a good size. I wouldn't want to use a smaller one, but I'd still use even the smaller one over the plastic ones.And it'See full review