Personalized Ohm Mighty Dark Products Long Sleeve T-Shirt. Tickle the funny bone of your favorite science geek with this design for birthdays, holidays, back to school and graduations for your favorite scientist Pre-shrunk 100% cotton 6.1 ounce long sleeve t-shirt. Double-needle stitched neckline and sleeves. Quarter turned. Shoulder-to-shoulder taping. Adult: S, M, L, XL, 2XL, 3XL