Personalized Heart New Big Sister T-Shirt. Future Big Sister T-Shirt - White Announce that you are going to be a big sister with this blue heart design. 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.