These cute sneakers/booties are snug but will stretch a little after use and are surprisingly warm despite the thin material. Even after walking for more than an hour at 3°C, my feet were still warm. I ordered my normal size (9) but they are a bit thin so I don't think they have enough room for thick socks. I haven't tested how they hold up in rain or snow but given the material I don't think I'd want to risk it. I will only use them on dry but cold days.