Personalized Monkey First Birthday Long Sleeve T-Shirt. It's my first birthday! This cute little monkey is celebrating his 1st bday! Happy birthday 1-year-old. 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