9M Men's Ultra Soft Thermal Underwear Base Layer Long Johns Set with Fleece Lined ULTIMATE WARMTH: Our thermal base layers are designed to keep warm without overheating you. The moisture wick properties will keep you just at the right temperature throughout the day. Once you put them on, they will feel like a second skin to you. HIGH WARMTH TO WEIGHT RATIO: We use special patented microfibers to produce the micro-fleece lining to maximize thermal insulation. These are thin and lightweight yet they perform much better than others on the market to provide you with the body heat insulation you need to get through the winter. SUPER COMFORTABLE: The ultra-soft microfibers make this thermal base layer one of the most comfortable thermals available. The rich microfiber material makes you forget that you are wearing anything under your daily clothing of choice. ULTRA VERSATILE: These thermal base layers can be worn under you daily work clothes or can be worn on its own for athletic activities, winter sports such as (Skiing, Snowboarding, Riding on motorcycles during Spring and Fall), and pajamas. Great for lounging indoors as pajamas &amp; Ourdoor use (Ski, Snowboarding, Winter Activites).