Personalized Mechanical Heart Toddler Long Sleeve 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. A classic for Fall, Winter and Spring, these long sleeve toddler t-shirts are sure to be a staple in your child's wardrobe. Whether layered or alone, this t-shirt is soft yet durable enough to stand up to your toddler's playtime demands.