Seems to be doing what we wanted.

DId not have holes for a roll cover.

I am not completely sold on the idea that this unit actually heats the water. In fairness, the weather was not exactly conducive. I'm sure the blanket helped in a small way--and it kept some of the leaves and things out of the water. But our local temps varied all over, so it might look promising one day but not at all the next. (Welcome to Texas!) I'm not a believer in "miracle in a can", so I was not disappointed. I am curious to see if it extends swimming into the fall. It didn't really help with early swimming this spring--but again the weather was no help. Cost is very reasonable, and it is worth the try.