Keep Feet Warm: These Below Zero socks use the latest fabric technology originally designed for aerospace to prevent your feet getting cold or damp in winter. They’re made of a breathable nylon knit interwoven with soft, fine aluminised threads that reflect your own natural body heat. Versatile: They’re durable enough to wear on their own or can be worn underneath a second pair of socks. Perfect Gift: These socks are the ideal present for yourself or a loved one for Birthdays or Christmas! Specifications: 1 pair supplied. Available in 2 unisex sizes: S/M to fit shoe size 5-8 and L/XL to fit 8-12. Machine Washable.