ULTRA SOFT FABRIC - The outer layer and inner lining are 100% combed cotton, and the inner filling is 100% polyester fiber that feels very smooth and gentle against baby's sensitive skin. The winter sleep sack for baby with a TOG rating of 3.5 is suitable for cool spring, autumn and chilly winter nights, usually woking well at room temperatures 53.6 °F and below | DESIGN FOR DIAPER CHANGING - Our warm baby sleep sack adopts smooth 2-way zipper and side open zipper system. Unziping from the top makes it easy to place baby in sleepsack, and unzips from bottom up, easy to change diapers, no worrying about the baby catching cold | ROOMY SLEEPING BAG - Our toddler sleeping sack adopts loose fit design to ensure sufficient space for movement. According to baby's growth and development needs, the leg area is designed spacious and suitable for the baby's natural frog leg posture and free kicking, which is conducive to the baby's hip development | THOUGHTFUL DETAILS - Our 3.5 TOG sleepsack pays great attention to workmanship and details. Zipper protectors on the top will protect baby's jaw from scratches, making it safer for baby. Product quality is our primary goal, we guarantee that every sleep bag will fully protect baby and ensure comfort for baby | WARM TIPS - Please refer to our size chart carefully before you order our sleep sacks. Hand wash is recommended, or low temperature machine wash. You could contact us with any questionyou may have at any time. We are willing to offer the most sincere help.