Personalized 1st Birthday Monster Long Sleeve T-Shirt. 1st birthday monster Long Sleeve T-Shirt - White. A cute monster holds a bright yellow balloon to celebrate the one year old's first birthday! Great gift for your little monster! 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