Personalized 4th Birthday Girl Mermaid Theme T-Shirt. Celebrate her special day with this vibrant 4th Birthday Girl mermaid-themed T-Shirt - Vintage Black. Featuring a colorful mermaid tail and ocean elements, it's perfect for little sea enthusiasts. 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.