Personalized Happy Pi Day Robot Math Class Men's V-Neck T-Shirt. Pi Day Men's V-Neck T-Shirt - White has funny vintage style robot and math symbol Happy Pi Day celebration logo. 4.7 oz., 100% pre-shrunk cotton Narrow, set-in 1x1 mitered V-neck collar Shoulder-to-shoulder taping Double-needle stitched sleeves and bottom hem