Coding explained - Hexadecimal 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 Coders like to say things in a different language other than their native tongue. Why not give your clever geek friend or loved one a shirt that speaks their language? Lightweight, Classic fit, Double-needle sleeve and bottom hem