Personalized Mechanical Heart T-Shirt. A mechanical gear heart design to tickle the funny bone of your mechanic or mechanical engineer at birthdays, holidays, graduation and Valentine's Day. 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.