100% cotton. Snap closure. High quality | soft cotton fabric, lightweight and breathable. Practical design | easy on /off boy crewneck shirt and pants with elasticized waistband which non-slip and painless. Occasion | little boy short sleeve pajamas can be used as play-wear at home in winter or with coat, blouse, cardigan, jeans, jogger pants, sweater, jacket or hoodie. Ideal for daily wear, outdoor, home wear or as sleep wear.