I bought a couple pairs of these because I work in a very cold office, and it's coldest near the floor, so I have to layer up my feet and lower extremities if I want to be comfortable during the cold months. I work weekends, and it seems even colder with just me and the skeleton crew in the building. These are extremely comfortable and have kept their shape for the few months that I've owned them, with no signs of defect or failure, so far. I will probably buy more, since these are working so well for me.