The Backcountry Cedars Rws Merino Lightweight 1 / 2 - Zip Scuba Baselayer Top utilizes techy, responsibly sourced merino wool to make the most of this unique, sporty silhouette. A scuba - style hood with a half - length zipper offers a snug under - helmet fit with high ventilation. The next - to - body profile features gusset - integrated raglan sleeves to maximize arm mobility and on - seam thumbholes to keep the sleeves in place while we're on the move. Our newest baselayer program features lightweight construction for our most athletic and active adventurers. We thoughtfully selected Responsible Wool Standard - certified merino wool fibers, which offer natural softness, thermoregulation, and odor resistance. Knitted with nylon for durability and spandex for comfortable stretch, this earth - and animal - friendly fabric is ideal for all our high - output winter adventures.