The Madison Isoler Merino Winter Cap is a perfect under helmet accesory for cold weather riding.  Madison Isoler Merino Winter Cap Features Shaped to work underneath a helmet with minimal seam irritation Unlike man-made fibres, Merino wool retains its thermal properties when it's wet to better regulate the body's temperature Peaked brim keeps the sun or rain away from your face Fold up rear panel allows you to expose the ears if you begin to overheat Limited lifetime warranty