The Patagonia Capilene® Air Hoodie is a super versatile base layer made from Patagonia's new "Air" fabric - a blend of 51% Merino wool and 49% recycled polyester. It's a mid-weight layer with an extremely wide comfort range and little bulk, thanks to the lofted wool construction that traps heat and allows first rate breathability. The added hood gives you one more option when it's really cold or the nasty wind kicks up.