Personalized Mind Gymnastics T-Shirt. Your brain needs exercise to stay in shape and Puzzles are Gymnastics for the Mind. Remind your friends to sharpen their minds with puzzles by sporting this design. Wardrobe essential for looking good, 24/7. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar. Shoulder-to-shoulder taping. Double-needle stitched sleeves, bottom hem and front neck. Note: greys are a cotton/polyester blend.