Cotton and fleece Imported Softness and Warmth - Yoofoss baby sleep sacks made with 2 layers, plush fabric and 100% cotton Lining, super soft and smooth, ensure baby's warmth and a cozy embrace. 1.5 TOG sleep sack is suiable for moderate temperatures from 69 to 73°F as an ideal option for autumn,early winter and spring or taking a nap in air-conditioned rooms during the summer, keeping your baby snug and warm. Healthy development - It's plush heart dots surface helps baby fall back to sleep quickly, transform the sleep sacks into an invaluable ally for moms, aiding in lulling their precious ones to sleep while fostering infants'cognitive development. Our baby sleeping sack provides ample room for kicking freely, ensuring your baby stays comfortable throughout the night while promoting healthy hip development. Hidden 2-way Zipper - Hidden zipper and neckline design to avoid any potential scratching baby's delicate skin. Double zipper allows for effortless dressing and making nighttime changes easier. The high-grade zippers of sleep sacks for baby glide smoothly without getting stuck or jammed, easily open and close. Safety Sleep - Yoofoss baby sleep sack is certified to meet Consumer Product Safety Commission (CPSC),dedicating to ensure your baby's safety and coziness. Fitted neckline and Sleeveless design provides appropriately flexibility and snugness, while better regulates your baby's temperature and reduces the risk of over-heating. Machine Washable - The baby wearable blanket come with 2 pack, convenient for the baby to change at any time. There are 4 sizes available sleep sack for your choices: S for 0-6 Months; M for 6-12 Months; L for 12-18 Months; XL for 18-24 Months. Please measure your baby's height and weight and refer to our size chart carefully before choosing. These baby sleep sacks are machine washable, tumble dry at low temperatures(