Before I bought it I up at 6.45am because it had been so hot. After I bought it, I could actually lie in. Amazing bit of kit which also protects the roof from really hot sun and thundering rain storms. Also kept the tent warm at night. I put the foil side on the inside, but I know you can have it facing out, not sure what the effects would be though. Also very easy to attach as long as you put it on while the tent is flat.