Breathable: The aluminium plated fiber fabric allows for air flow and breathability to avoid sweaty feet! Health benefits: These heated socks aim to help increase circulation and blood flow. Size: One size fits all. Energy saving: These socks are hot stuff! Constantly self-heating, maintaining 35℃ heat without having to turn the heating on. Material: Made of cotton, polypropene and aluminium plated fiber. Socks: Get energy saving self-heating thermostatic knee high socks.