When temperatures fall, feet can be the first to suffer. Ordinary thermal socks or wearing many pairs of socks will let you down. To be confident in the cold you need a sock with high insulation. Heat Holders have been tested to achieve a tog rating of 2.34. The unique 3 stage process using heavy bulk yarn, patented knitting technology, and intense brushing holds more warm air close to the skin, ensuring your feet stay warmer for longer.