Anne K.wrote a review of Sierra Designs Drizone Packable Bootie Slipper - Women's on April 8, 2009
I bought these to sleep in since I get very cold feet in my sleeping bag. They were not as thick as I had expected, but they were comfortable. I wore them over a thick pair of wool socks and my feet stayed warm. Without them, I would wake up with feet of ice, so they obviously did the trick. However, if the temps were much below 25F, I would upgrade to some down booties.
I wore them around camp while making dinner, etc. and they held up well.