Personalized Ruler Toddler Long Sleeve T-Shirt. I am the ruler text with a ruler replacing the letter L in ruler is a humorous gift design for back to school, birthdays and holidays. 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.