We select high-quality 100% natural organic cotton as the fabric, which can be combed repeatedly to remove impurities and retain the softness of the fabric itself. The fabric does not add chemical agents, it is completely soft and safe. It will not make babies allergic and il will not pilling. 4 Suitable fitting sizes for babies aged 0-24 months: We have adjusted the most suitable neckline for babies of different ages. It will not be too big to make baby’s head slip into the sleeping bag and cause danger, and it will not be too small to make baby choking. The proper tailored size that covers the shoulders and contains the rest of the body with the arms outside of the sleeping bag helps to prevent overheating. Smooth and durable. The 2-way fastening zipper design makes it easier for you to dress your baby with our swaddle blanket. The well--tailored neckline makes the sleeping bag more fit. Not too tight to cause suffocation, nor too loose to cause the baby’s head slip into the sleeping bag causing danger. The unique sleeveless design helps reduce the risk of overheating. Safe dyeing on 100% organic cotton fabric: We use the latest and improved digital printing and dyeing technology in 2020, which is absolutely safe and non-toxic. Not sensitive. No peculiar smell. The bodysuits will not decolorize. All for your baby. Enough room to allows your baby to adopt a natural “frog-legged” sleeping position for hip development, which lets them naturally move their legs and hips for comfort. With 1 zipper from the bottom, you can easily pull the bottom zipper to change easily the baby's diapers.