Base layers are more than just any old underwear - they wick moisture and help out the shell you are wearing. For example, the 509 FZN Level 1 Base Layer Shirt wicks moisture into the outerwear above, keeping wet and cold off your skin. Experience the comfort and performance difference using 509’s Active Layering System™ featuring Cold Armor™ technology. Cold Armor™ is a blend of technical materials constructed to wick moisture and create a cold blocking barrier for those frigid days. Pairing 509’s base layers with 509’s outerwear creates a high performance layering system that works together to keep you dry and comfortable. Starting with our lightest base layer, the LVL  is a next to skin layer designed to be close fitting and actively work to wick away moisture creating a comfortable in even the harshest conditions.