STEM - Science Technology Engineering Mathematics (Original) 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 BEWARE OF COPY CATS!! STEM - Science, Technology, Engineering, Mathematics, Mechanical, Electrical, Electronics, Civil, Industrial, Design, Computer Science, Statistics, Biology, Chemistry, Physics, Biotech, Instrumentation, Hardware, Internet STEM, Students, Professionals, Doctors, Programmers, Electrical, Mechanical, Computer Science, Biotech,Statisticians, Data Geeks, Product Managers, Physicists, PhD, Masters, Information Technology Lightweight, Classic fit, Double-needle sleeve and bottom hem