Personalized This Little Monster is One T-Shirt. This Little Monster is One! A cute little green monster smiles because it is now one year old. Great birthday gift for your little 1 year old monster. Wardrobe essential for looking good, 24/7. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar. Shoulder-to-shoulder taping. Double-needle stitched sleeves, bottom hem and front neck. Note: greys are a cotton/polyester blend.