I have to have my Stretchwick cover on my mattress to keep the warranty active. It makes me hot at night. I put a beach towel on the bed before I put on the sheets to keep from perspiring. I must say it is better then most mattress covers. After a couple of years it needs to be replaced. The waterproof skin on the back does separate from the fabric. This is my second one in two years, I bought one when I bought my bed. The workmanship is very good. Kind of pricey to replace every few years. light weight. Does have a tendency to stretch out.