PRICES MAY VARY. Solid colors: 100% Cotton; Heather Grey: 90% Cotton, 10% Polyester; All Other Heathers: 50% Cotton, 50% Polyester Imported Pull On closure Machine Wash Funny gift idea for chemical engineers, nerds, geeks, chemists, etc. I May Be Nerdy But Only Periodically, Chemist, Chemfical Engineering Gift Ideas. Lightweight, Classic fit, Double-needle sleeve and bottom hem