The Windstopper booties are super lightweight and super small to pack and are then used when the feet need heat and relaxation! They are ideal for people who have cold feet in their sleeping bag and are perfect for an overnight visit to a cabin. Insulation: G-LOFT(R) Si 250g/m², 100procent Polyester Outer fabric: Gore Windstopper(R), 100procent Polyamide Inner lining:  100procent Polyamide Sizes: M (36-40), L (40-46) Weight (g): 300 (Size M)