Personalized Happy 100 Days Of School T-Shirt. This Happy 100 Days Of School design apparel is a great way to commemorate a memorable milestone in your child's academic journey. Whether as a gift or for your own child, this cute and happy design will capture the excitement and achievement of reaching the 100-day mark. Get yours today and make the 100th day of school even more special! 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.