NWT. Size large swaddle for babies 12-18 lbs Elevate your baby's sleep experience with the Swaddle Sleep Sack, the world's first 3D knit seamless swaddle offering the perfect blend of comfort, safety, and freedom. This sleeping sack creates an environment for serene and self-soothing sleep. Adaptable as your child grows or rolls over, it transitions into a wearable blanket for increased movement, making it a thoughtful and practical gift for new parents.