Safety Comes First: Made of 100% premium cotton layers and soft polyester filling to guarantee the utmost comfort and protection of baby's sensitive skin. Yoofoss baby sleep sack is certified to meet Consumer Product Safety Commission (CPSC), dedicating to ensure your baby's safety and coziness, and adopt eco-conscious prints for a safe and stylish look. | 2.5 TOG for Warmth: with a 2.5 TOG rating, our sleep sacks meticulously designed for the cold seasons, ideal for room temperatures ranging from 50-68°F. This exceptional baby wearable blanket is thoughtfully crafted to create a snug and inviting sanctuary for your little one. | Large Space And Sleeveless: The ergonomically designed baby wearable blanket features a bell-shaped bottom to promote healthy hip joint development, spacious space allow baby to move more freely and stay comfortable while they sleep. Sleeveless design provides for greater flexibility and comfort, better regulates your baby's temperature and reduces the risk of over-heating. | 2-Way Zipper and Available Sizes: The top-grade double zipper allows unzip from the bottom for fuss-free diaper changes without disturb baby during the night, and design with zipper garage to protect baby’s face from chafing. There are 4 available sizes for this baby sleep sack; S for 0-6 Months. M for 6-12 Months. L for 12-18 Months. XL for 18-24 Months. | Mahchine Washable: Ensure you buy the correct size for your baby's weight, to prevent the sleep sack from riding up around your baby's face. This baby wearable blanket can withstand hundreds of washes without fading, and its advanced technology ensures a shrinkage rate of less than 3% after machine washing and dry on low heat (<30°C/86°F).