Neither - it’s Tencel (Lyocell) - a fiber made from the wood pulp of trees that are grown and replaced on specialized tree farms. Tencel is produced using recyclable, Earth-friendly solvents. Fabric made of Tencel lyocell also has excellent drape, doesn't wrinkle easily, and holds dye well so it makes vibrant colors. It's also breathable and manages moisture so it helps with temperature regulation.
@4842 It’s actually made of Tactel Nylon. a Tactel is a synthetic nylon yarn, characterized by much better properties than classic cotton and other natural materials. ... Tactel is 3 times more durable than natural fabrics, dries much faster than classic cotton (manufacturers say about even 8 times shorter drying time), and additionally it's light and airy.