Pirate pi rate shirt for pi day math pirates tshirt Solid colors: 100% Cotton; Heather Grey: 90% Cotton, 10% Polyester; All Other Heathers: 50% Cotton, 50% Polyester Imported Machine wash cold with like colors, dry low heat Lightweight, Classic fit, TearAway label, Double-needle sleeve and bottom hem 4.5 oz 100% Combed Ringspun Cotton, machine wash cold with like colors, dry low heat