86% Polyester, 14% Spandex Made in the USA or Imported MIDWEIGHT BASE LAYER - The adventure is yours, we'll keep you warm and comfortable; The Hot Chillys Base Layer for men is designed for performance and wearable comfort in any season; This men's underwear features a crew neck, long sleeves, and hidden thumbhole loops; Made of a buttery soft, cottony hand Clima-Tek fabric with all of the performance of a polyester/spandex, the active undershirt is ready for outdoor activities RELAXED FIT - The Clima-Tek Crewneck Base Layer is designed with a looser fit that lies gently on the skin without binding; Despite the relaxed fit, the fabric consists of 86% Polyester, 14% Spandex, so the silhouette accommodates movement; This men's long sleeve thermal shirt is perfect for summer camping in the mountains and winter wear anywhere WARMTH FACTOR - Ranked from mild to hot, the Warmth Factor Thermometer tells you how warm is your thermal underwear; Warmth Factors 6, 7, and 8 are considered Midweight and are very popular for most cold-weather activities; The Hot Chillys Men's Thermal Shirt has a warmth factor 7 out of 10, as it features a lightly brushed stretch fabric, that provides warmth in cold conditions; At the same time, this long sleeve shirt for men with UPF 30+ also protects you from sunlight 4-WAY STRETCH - The durable and breathable fabric with the elastic feature will hug your body, so your long sleeve undershirt will move with you, eliminating extra bulk and providing a full range of motion, as well as improving performance; Nearly all of Hot Chillys body-fit products include a 4-way stretch for unlimited movement ACTIVATED CARBON - The Hot Chillys activated carbon enhances thermal regulation, while moisture transfer fibers move moisture away from skin to keep you dry; You will look good and feel better in Clima-Tek fabrics with OBP label, with unbeatable breathability and temperature regulation to keep you comfortable in any conditions; This Base Layer is a perfect men's top, designed to be lightweight, quick-drying, and moisture-wicking to keep you feeling refreshed no matter how active you are