Personalized 100 Days Of School 100 Days Of Cool T-Shirt. Celebrate your child's milestone with our adorable "100 Days Of School 100 Days Of Cool" design apparel. This cute and happy design is the perfect way to commemorate your little one's first 100 days of school. 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.