The transitional swaddle Sack is designed to bridge the gap from swaddling to sleeping sack. When baby is ready to transition from a swaddle, but not ready for a sleeveless wearable blanket. The transitional swaddle Sack is perfect for babies who prefer to sleep with arms up. The Swaddle Sack supports baby in a back sleeping position and allows for multiple arm and hand positions to help baby sleep better. The transitional swaddle Sack with partial suppression of the Moro (startle) reflex, and the arms up sleeve design is a safer sleep solution. If baby rolls over, the design allows baby to use their arms to lift their torso and reposition his or her head to get access to air. The Swaddle Sack uniquely shaped arms up 3/4 Length sleeves are not full length, so baby's arms will be close to body when mitten cuffs are closed for swaddle snugness. The patent pending sleeve design are not full length "by design." When the mitten cuffs are closed and baby is placed in the Swaddle Sack, The uniquely shaped arms up design positions baby's in a flexed, close-to-body, arms-up position, and shape and length of the sleeve helps partially suppress the startle reflex. Parents are encouraged to close the cuffs first, and then place baby in the sack. If the caregiver wants to allow baby to suck directly on hands, then open one or both of the mitten cuffs. The 2-way zipper makes the Swaddle Sack easy to use for the caregiver. The zipper has two zipper pulls - one at the neckline and one at the foot of the sack. Winner of multiple awards. Recognized by the International Hip Dysplasia Institute. The lower section is less spacious than a typical sleeping sack, and in turn, the Swaddle Sack provides some suppression of the startle reflex for the legs. The hip healthy design allows baby's knees and hips to flex. Premium cotton. Made from premium, interlock Cotton knit. Machine washable. Swaddle Sack is a registered trademark of SwaddleDesigns. Patent pending.