Name: Heat Holders
What they are: Thermal socks designed to hold warm air close to the wearer's feet, keeping the feet warmer than standard thermal socks. Made with a special insulating yarn and an innovative knitting technology, they have a TOG rating of 2.34 (a Thermal Overall Grade is a measure of a material's thermal ability). By comparison, ordinary thermal socks have a rating of 0.89, and basic cotton socks are a puny 0.33.
The good: They do exactly what they promise. I walked for 30 minutes in below-zero temperatures, and my feet stayed warm and perfectly comfortable — not hot and sweaty as might happen with battery-powered socks. I wore them under a pair of thin moccasins in 25-below wind chills while walking a dog, and again they kept my feet perfectly warm. Worth noting: The brushed interior material is remarkably soft. The word "plush" comes to mind. Also, the manufacturer has trademarked the term "Gentle Grip" for the fit. It's appropriate. Heat Holders are machine-washable.
The bad: They are thicker than many thermal socks, so if you have tight shoes, the Heat Holders will make them that much more snug.
Cost: $15.99 a pair for the basic men's socks, which come in a variety of colors. There also are women's and children's sizes, and different styles; prices vary.
Available from: heatholders.com