Embrace the shoulder seasons with the NRS HydroSkin® 0.5 Helmet Liner. Fits easily under any helmet, adding just enough insulation for those colder spring and autumn days.0.5 mm of neoprene provides the core insulation for this helmet liner. Four-way-stretch ; exterior material helps mold the liner snugly to your head.The soft; lining adds a bit of extra warmth and feels great against your skin.Titanium-laminate adhesive reflects and retains body heat for superior warmth. Durable Water Repellant (DWR) treatment helps shed water preventing evaporative cooling.