What is Supima®? Only the best cotton grown in America, with 35% longer fibers that feel smoother, take dye better and are 45% stronger than lesser cottons. It's rare, too. Less than 3% of American cotton is fine enough to wear the Supima name. So you know it makes for an exceptionally comfy and colorful robe. The one you’ll love first thing in the morning or while settling in at the end of your day.