I dunno about those slits. They should close up when you install it, but they will still be there! I had my old one recovered with foam backed material.
Yeah, that's what I don't get. My old one looks like it had slits, but they were together and had a seam filler of sorts. Just looked like a line of some kind of filler.
I would have done the same, but a rat decided there wasn't enough holes in it....... :(
