Personalized I'm Going to be a the Big Sister T-Shirt. Celebrate the arrival of a new sister with our elephant-themed toddler apparel and accessories. Our designs are perfect for the older sister to show off her new role in the family. Check out our collection today! 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.