Stay warm and dry in the harshest conditions with 509’s Active Layering System featuring Cold Armor technology. Pairing 509’s base and mid layers with 509’s outerwear creates a high-performance layering system that works together to keep you comfortable no matter what. The system starts with our lightest base layer, the 509 FZN Base LVL 1 Pant—a close fitting next-to-skin layer designed to actively wick away heat-robbing moisture so you stay dry and comfortable all day long.
