A onesie is known as a Romper, One-pieces, Bodysuit. 65% Polyester 35% Cotton 5.6 oz interlock knit - Screen Printing, Embroidery, Applique & Sublimation Printing Kimono style bodysuit wraps baby in total comfort and style. Nothing is pulled over baby's gentle head with this smart wrap-around design. Open up the onesie just like a shirt and place your baby inside. CPSIA Approved for safety and comfort.