The cotton fabric of this long-sleeved pajama set with a button-down collar gives you a soft and smooth feel. It makes you feel comfortable and free all day long. Cotton is a natural fiber. Made of pure cellulose. It consists of cellulose. It is an organic substance that is synthesized in nature. It has little flexibility. Care instructions. Wash at 30 degrees maximum. Do not tumble dry. Do not use bleach.