This is only a single layer of interlock wool. The older version had a doubler layer. These have not worked overnight yet for us. I think they will be fine for day use, but I specifically bought these for overnight, and I don't think they are thick enough.
Reviewed by: HOLLY from Kansas .
This is a nice cover runs true to size. It is soft. Not my favorite but I do use it a lot. It is a little expensive for what you get but it stays nice and stretchy!