The advantage of the thermal liner with its micropolar lining is its insulating foam composition, which doesn’t retain any moisture near the foot. Unlike natural materials such as felt or wool, which attract and retain water, insulating foam expels water or moisture from the thermal liner to the outside, while retaining your warmth. By staying dry, the boot’s thermal performance remains optimal. What’s more, the heel is reinforced. Firm but elastic, it conforms to the shape of your foot, ensuring maximum comfort and warmth!