Personalized 4th Birthday Mermaid 4 Year Old Women's V-Neck T-Shirt. This cute mermaid themed number 4 is just right for a little girl celebrating her 4th birthday party. 5.0 oz., 100% pre-shrunk cotton Athletic Heather is 90/10 cotton/polyester 1x1 rib collar with mitered v-neck Shoulder-to-shoulder taping Ladies' fit