90% Modal, 10% Spandex Imported Machine Wash MOST COMFORTABLE LOUNGEWEAR ON THE PLANET – We use only the finest, most luxurious stretch fabrics available and have changed the men’s pajama category with our silky-soft, non-pilling fabric. MEMORY COLLAR PREVENTS BACON NECK – Reengineered with our lay-flat, stretch rib collar, this long sleeve will not stretch, giving you a new tee look for years to come. THE PERFECT FIT – Designed to fit your body and not a box, this Second Skin Sleep Long Sleeve feels smooth to the touch and soft on your skin. The micro-modal, spandex fabric blend moves with you instead of against you, providing an all-night comfortable fit. SILKY SOFT & BREATHABLE – Micro modal is made of natural beechwood fibers, for an ultra-soft feel you’ll love to wear. This comfortable fabric also makes this ultra breathable, keeping you feeling cooler than cotton alone. SIZING MADE EASY – Our sizing is measured by chest size. Measure under the arms and across the fullest part of the chest apex including the lower portion of the shoulder blades. Small fits 34-37 chests, medium fits 38-41, large fits 42-44, XL fits 45-48, and XXL fits 49-52 chests.