Caffeine Molecule Coffee T-Shirt Coffee Lovers Funny Gift 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 Coffee science shirt formula C8H10N4O2 Caffeine molecular structure 1,3,7-Trimethylpurine-2,6-dione Lightweight, Classic fit, Double-needle sleeve and bottom hem