Rechargeable Heated Socks for Men & Women - 7.4V 2200mAh Battery-Powered Winter Warm Socks - Thermal Foot Warmers for Cold Weather - Perfect for Hunting, Skiing, Camping & Outdoor Activities

Bought these socks primarily for skiing. After initially charging the 2 batteries I discovered that one of the battery packs was faulty. Contacted the seller and they shipped out a replacement free of charge. I've skied in the socks a few times and they generally work well. We were up in Canada and the temps were below 0F (started the day at around -5F) and my toes didn't get their usual cold. Also wore them in my snow boots while dog sledding in 0F temps (why don't the dogs get cold feet?) and they worked fine. Only issue that I've found is that you have to pay attention to them as you put them on. There is a wire running down the sock and you don't want it against your ankle bone while wearing ski boots as it can cause some discomfort - but that is solved simply by rotating the sock so that the wire is behind the ankle bone.For reference I wear size 11 shoes and purchased the socks in a size large. They are snug on the upper calves but that stops them from falling down. The battery pocket is formed from a separate piece of material and it is easy to insert the battery into the pocket.