It's closed cell foam. A bit spendy for what you get plus shipping. I cut it with an extra long razor blade so u could keep the sticky backing intact. When I peeled the backing paper away all the glue came with it. I'm using this piece in my shower and oversized the piece to squish a bit. It seems to have shrunk. Only slightly, but a noticeable amount. I may have to cut another from what I have left over that's extra thick for better fitment. Overall it serves its purpose.