Personalized 3rd Birthday Mermaid 3 Year Old Girl T-Shirt. Cute mermaid themed 3rd birthday outfit for a toddler girl with number 3 design. 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.