The Transitional Swaddle Sack is the best & safest baby sleep sack when it is time to transition baby from a swaddle that restrains baby's arms. The TSS features an arms up sleeve design that allows baby to self-soothe. The patented arms up ½-length sleeves with foldover mitten cuffs closed provide gentle suppression of the Moro (Startle) Reflex to promote better sleep. The uniquely-shaped sleeve design is safer because if baby rolls over, the sleeves allow arm mobility so baby can use arms to reposition by lifting their torso and head to access air for safer sleep. The Transitional Swaddle Sack is ideal for babies who prefer to sleep with arms up, babies who are starting to or able to rollover, babies who like to suck on hands to self-soothe, and for babies who get out of a classic swaddle. Our special sleeves position baby’s arms close to their body in a flexed position and when mitten cuffs are closed, the sleeves provide gentle suppression of the Moro reflex, so baby sleeps better The foldover mitten cuffs may be worn open or closed; caregivers can open one or both cuffs, so baby can self-soothe by sucking directly on hand, or close the cuffs to protect baby from facial scratches. Helpful 2-way double-pull zipper with zipper guard to protect baby's skin; zips down from the top to make it easy to place baby in the sack and zips up from the bottom to make it easy to change baby’s diaper. 100% Cotton. Soft, stretchy, breathable fabric. 0.5 TOG for moderate temperatures. In cooler settings, parents can layer with a bodysuit underneath and/or sleeveless wearable blanket such as the Amazing Baby zzZipMe Sleeping Sack. Machine wash warm and tumble dry low. Recognized by the International Hip Dysplasia Institute (IHDI) as Hip Healthy. Designed by a nurse. US patents 11,812,795 & D833,613; EU, UK, CA, CN, and other countries online.