Staying warm in the mountains during winter means layering up with insulating, breathable baselayers that won't hold moisture as you sweat, and the Arc'teryx Women's RHO LTW Zip Neck Top does just that. Made with a blend of merino wool sourced from New Zealand and a touch of elastane for stretch, the RHO is insulating, breathable, and naturally antimicrobial, making it a great baselayer for backcountry hut trips and cold weather mountaineering endeavors.