Personalized I'm A Triathlete Toddler T-Shirt. Triathlon athlete Toddler T-Shirt - Black for the competitor in your life who enjoys biking, swimming and running says I'm A Triathlete. Perfect for that next competition. A toddler-soft cotton tee in look-at-me, big kid colors. 4.5 oz., 100% combed ringspun cotton. White is sewn with 100% cotton thread. Topstitched rib crew neck. Double-needle stitched sleeves and bottom hem. Shoulder-to-shoulder taping.