Made of 65% polyester and 35% combed ring-spun cotton, this super silky fabric is lightweight and stretchy yet durable. They are personally my favorite to train or lounge in. Not as soft as a triblend, sure, but those lose their luster more quickly and don't breathe as well as cotton. On the other hand, too much cotton and it can be scratch and uncomfortable (plus they shrink). 65%-35% offers the best of both worlds.