Personalized 100 Days Of School 100th Day Party Long Sleeve T-Shirt. Cute 100 days of school Long Sleeve T-Shirt - White 100th day party celebration apparel. Pre-shrunk 100% cotton 6.1 ounce long sleeve t-shirt. Double-needle stitched neckline and sleeves. Quarter turned. Shoulder-to-shoulder taping. Adult: S, M, L, XL, 2XL, 3XL