100% Premium Cotton: Made of 100% cotton to guarantee the utmost comfort and the protection of toddler's sensitive skin. Yoofoss baby sleep sack with sleeves is certified to meet Consumer Product Safety Commission (CPSC), dedicating to ensure your baby's safety and coziness. | Long Sleeves with Mitten Cuffs: Long sleeve baby wearable blanket provides free arm movement and warmth for your little one when napping in cool summer A/C room, sleeping at chilly spring,autumn and winter nights. What's more, baby sleep sacks with eversible mitten hand covers can avoid facial scratches for infants. | 2-Way Zipper: Double zipper allows for easy dressing and convenient diaper changing with no hussle and bustle. Top-grade zippers and zipper flat design, sleeping sack for baby frees from any potential scratches, glide along the tracks moothly without any snagging or jamming, providing a sound experience for both parents and babys. | Safety Sleep: The neck opening is precisely tailored to provide a snug fit. Yoofoss newborn sleep sack with wide hem allows for your angel to move freely but not kick off, keeping warm and comfortable throughout the night and great for baby's hip development. | Easy Care and 4 Available Sizes: There are 4 sizes available sleep sacks 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 infant's height and weight, and refer to the size chart before choosing. This long sleeve baby sleeping sacks withstand multiple machine washes and reduce the household chores for parents.