Personalized Happy 100 Days Of First Grade T-Shirt. The Happy 100 Days Of First Grade design is specifically made for 1st-grade students, adding an extra touch of joy and pride to their big day. With its vibrant colors and adorable illustration, this design is sure to bring 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.