Personalized 100th Day 100 Days Smarter Arrow Youth Long Sleeve T-Shirt. 100 days smarter Youth Long Sleeve T-Shirt - White outfit to celebrate the 100th day of school in style. Cute hearts and tribal arrow design. youth long sleeve t-shirt. Shoulder-to-shoulder taping. Youth: S(6/8), M(10/12), L(14/16), XL(18/20)