Personalized Superhero 4th Birthday Pink Long Sleeve T-Shirt. Happy 4th birthday! Celebrate your toddler's third b-day with this cute I'm 4 pink superhero design. Happy Birthday four-year-old! 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