Heat Holders Ladies Thermal Leggings Small Black 1 pair of Heat Holders thermal leggings, available in 4 sizes and colours! These leggings are the best for thermal insulation against the cold. Advanced Insulating Yarn - High performance insulation against the cold, making sure you are your warmest even when it is freezing outside! Soft Brushed Inner - Maximises the amount of warm air held close to the skin, keeping you super warm for longer! 0.52 TOG - These have a massive 0.52 TOG rating - this is the measurement for thermal abilities, so you can be sure that these will keep you super warm.