Personalized 4th Birthday Monster Truck Toddler T-Shirt. I'm Four! A red monster truck drives over the words. Great fourth birthday gift for your favorite 4 year old. 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.