Oxygen & Magnesium OMG Periodic Table Science Chemistry Funny - T-Shirt Shirt Invaders exclusive design, created by our in house art department. 100% Preshrunk cotton t-shirts with a custom screen printed grapic on the front chest. Custom Printed using eco-friendly plastisol or waterbased ink to ensure color fastness and long lasting durability. Search shirtinvaders or check out our store to see our full product line. FREE SHIPPING options for all of our products!