Comfort Fit, the ribbed construction shapes to the contours of the body , Size Guide To Chest Size Small 36"-38" Medium 38"-40" Large 41"-43" XL 44"-46" XXL 48"-50" , 50% Cotton, 50% Polyester , Machine Wash , Fastening: Pull On , Short Sleeve , Also available in Short Sleeve Top and Long John Sets - Please visit our Storefront for our full range of Mens, Womens and Childrens Underwear, Socks and Accessories.