Heat Holders Womens/Ladies Extra Warm Thermal Slipper Socks (2.3 Tog) 91% acrylic, 5% nylon, 3% poly, 1% elastane Imported Machine washable Tog rating - 2.34. Ordinary Thermal socks are 0.89. Advanced Insulating Yarn - High performance insulation against cold with superior moisture wicking abilities. Long Looped Thermal Pile  Innovative knitting technology produces our unique, extra long looped cushion pile to hold in warm air, increasing the thermal Tog rating. Soft Brushed Inner  Finally, an intense brushing process maximises the amount of warm air held inside the sock for all day warmth and comfort. Heat Holders - Best seller since 2010, providing a wide range of winter thermal products that we provide in the sock snob online amazon store