Personalized Superhero 6th Birthday Pink T-Shirt. Happy 6th birthday! Celebrate your child's sixth b-day with a cool SUPER 6 superhero party. Happy Birthday six-year-old! Everyone loves our Custom T-Shirts! 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.