Great emergency bivvi
I really like this product. I've always carried a few space blankets in case I get benighted on a long distance walk, but this is so much better as it keeps the wind completely out. Pair it up with a foil jacket and maybe a space blanket and you could survive a really nasty night out on the fells in relative comfort. I'd recommend this to anyone doing solo fellwalking, along with a survivajak or two.