What is Supima? Only the best cotton grown in America. With extra-long fibers that feel smoother, they take dye better and last longer than lesser cotton. It s rare, too — less than 3% of American cotton is fine enough to wear the Supima name. So you know it makes an exceptional tee. With a flattering henley neckline and short sleeves, it s guaranteed to slip into your must-wear rotation. Supima is conscientiously sourced, American-grown cotton farmed to minimize environmental impact.