100% Cotton Warm and Cozy - This baby sleep sack made with 100% Organic cotton fabric and fluffy polyester filling, super-soft and breathable for comfort. TOG 2.5 sleep sack is ideal for cooler weather. 3-layer breathable material and sleeveless design helps regulate baby's temperature, reducing overheating risk and ensuring warmth and cozy. Safety Sleep - Yoofoss baby sleep sack are CPSC-certified for your baby's safety and comfort. The neckline has been carefully sized and numerous experiments ensure a secure and snug fit, preventing the baby from slipping into the sleeping sack. And the loose around the legs to allow for natural hip development. Long Last Quilted Design - The unique quilted design ensures even distribution of fill, prevents lumping or shifting, improves durability while reduces shrinkage compared to regular baby wearable blanket, and withstand hundreds of washes. We've improved the sleep sack to achieve a shrinkage rate of less than 2% after machine washing and dry on low heat. Smooth 2-way Zipper - Our Baby wearable blanket feature a double zipper, so you can unzip from the bottom to to change diapers, disturb baby even less during the night. Then you and enjoy a sweet night with little one ! Zipper protectors on the top will protect baby's jaw from scratches. Warm Tip: The winter sleep sack can be inner-layered with warmer sleepwear for chiller temperatures and suitable for room temperatures 61°F- 68°F . There are 4 sizes available for your choices: S(0-6Months/10-18lbs), M (6-12 Months/16-24lbs), L(12-18 Months/22-28lbs), XL(18-24 Months/26-34lbs).Please refer to our size chart carefully before you order our wearable blanket baby.