We purchased just one of these rings from Leisure Living to give it a try in our hot tub, before we bought any for the pool. Don't waste your money. First of all, you have to physically blow these things up like you would a raft. Secondly, I could not get the thing to lay flat like a solar blanket. Also, like some one else said, you would need about 30 or more of these things to cover an average size pool. My advise, don't waste your money, just get a regular solar cover.