Personalized Happy 100 Days Of School T-Shirt. Whether your child is celebrating their 100th day of school at home or in the classroom, our Happy 100 Days Of School design apparel is a must-have. It's not only a stylish addition to their wardrobe but also a special keepsake that they can cherish for years to come. Get yours today and let your child shine on their special day! 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.