I have been using junk boots for many years and it never really occurs to you what a good pair might feel like until you splurge on a pair. I went with the 400g insulated pair and they are so warm and comfortable. I do not need 2 pairs of socks. Perfect for shoveling or long hikes with the dog. Very versatile and seems very true to size. I wear a 9.5 shoe. With one pair of socks, the 9.5 was a perfect fit but the 10 was sloppy. with 2 pair of socks, the 9.5 wouldn't fit right and the 10 was perfect. with the 400g insulation there isn't any need for 2 pairs of socks.