Personalized Happy Pi Day Math Holiday Long Sleeve T-Shirt. Pi Day Long Sleeve T-Shirt - White has cute baked pie filled with math symbols. Fun shirt for students or teachers on Pi Day. 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