Castelli womens alpha jacketwith alpha weve detached the insulation layer from the windproof layer so that you can open the windproof layer while climbing to let air in to ventilate and help evaporate moisture when youve hit the summit zip up the windproof outer layer and enjoy a warm dry descent featuresarticulated collar that fits better whether standing or ridingwindstopper 150 fabric is windproof and water resistantbetter ventilation and better moisture evaporation thanks to separat