Personalized 100 Days if Growing | 100 Days Of School T-Shirt. With our 100 Days of School design apparel, your child will not only look stylish but also feel a sense of accomplishment. It's a great way to celebrate their hard work, dedication, and progress throughout the school year. So, make their 100th day extra special with our cute and happy 100 Days of School design apparel. 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.