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 with stretchable, poly-spandex blend for long-lasting wear. It is ideal for those working in construction, transportation, warehousing, refrigerated areas and more. Also wear this washable liner for weekend activities such as hunting, climbing, running, cycling and skating. One size fits most.