Personalized That Was Pretty Cool 100 Days Of School T-Shirt. Celebrate your child's milestone with our That Was Pretty Cool 100 Days of School design. This adorable and happy design is perfect for showing off their achievements and bringing a smile to everyone's face. 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.