Underworks Mens Microfiber Light Compression Crew Neck Long Sleeves T-shirt MicrofiberNylonSpandex Sizes: Measure Chest in Inches: Small 32-35 / Medium 36-39 / Large 40-44 / X-large 45-48 / 2X 49-52 / 3X 53-108 Comfortable to wear all day and everyday as a base layer or a top Smooth microfiber nylon stretches in all directions and conforms to every part of your body SPF 50 UVA protection Proudly made in the USA The new Underworks Microfiber Compression Crew Neck T-shirt with Long Sleeves feel like skin tight silk! Our fabric offers multi-directional stretching that allows the shirt conform to every curve of your body and move with you. Invisible under clothing. Breathable and cool. Micro-Fiber soft touch, is a man made synthetic fiber made by Dupont. These yarns are especially engineered ultra fine filament yarns in which each filament has a controlled thickness that is 15 times finer than human hair. The result is unmatched comfort, fit, and durability. Our microfiber also has an SPF 50 rating for your protection. Made in USA Fitness enthusiasts use them to complete their workout outfit They serve as a base layer underneath a shell or jacket for your outdoor colder-weather activities Made in USA M<span class="a-text-bold">EASURE YOUR CHEST: </span>With arms down on side, take a snug measurement around the fullest part of your chest over the nipples.H <span class="a-text-bold">OW TO WEAR: </span>Pull garment over head and adjust for comfort.H <span class="a-text-bold">OW TO CARE: </span>Wash in cold water, gentle cycle, tumble dry low or flat dry. No bleach, no iron.