Personalized Baseball 7th Birthday Youth T-Shirt. Happy 7th birthday! Celebrate your child's seventh b-day with a cool SUPER 7, superhero personalized gift. Customize and add your child's name. Happy Birthday seven-year-old! Let the good times roll in a durable T-Shirt that takes kids from school to play in an amazing array of colors. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar.