Personalized Happy Birthday Train Infant Romper. Happy Birthday! A cute choo-choo train filled with adorable animals chugs along the tracks bringing lots of birthday gifts! Meet your new favorite outfit! Keep dressing simple with this one piece, lap shoulder t-romper. Super soft and perfect for baby's sensitive skin. 5.5 oz. 100% combed ringspun cotton premium jersey (CVC Colors are 60/40; Heather is 90/10 combed ringspun cotton/polyester)