The Arch Rock 1/4 zip provides built-in temperature regulation with the warmth of a high neck or the increased airflow of the zipper. SUSTAINABLE DESIGN: 100% Responsible Wool Standard (RWS) wool, certified by Control Union cert. 895314. RWS certified Merino wool supports animal welfare, land health, and supply chain transparency. WARM & DURABLE KNIT: 5-gauge knit merino insulates on cold days without overheating. VERSATILE VENTILATION: The 1/4 zip design lets you adjust airflow on the move-zip up for warmth or down to cool off without removing layers. ALL DAY COMFORT: Fine 19.5 micron Merino wool is naturally soft, breathable, and less itch.