The N-Ferno 6813 Winter Skull Cap Helmet Liner is lightweight and breathable for warm comfort in mild to cold conditions. Designed to fully cover the head and ears, this low-bulk thermal skull cap can be comfortably worn on its own or beneath helmets and hard hats. With a brushed thermal interior and durable pill-resistant exterior, this winter beanie is made for long-lasting wear. This winter helmet liner is ideal for those working in construction, transportation, warehousing,