The Sleeping Baby Zipadee-Zip Swaddle Transition Sleep Sack in Blue is a medium-sized sleeping bag made from 95% viscose from bamboo and 5% spandex. Designed for babies aged 6-12 months, this unisex sleep sack provides a safe and comfortable sleeping environment. The zipadee-zip feature allows for easy and convenient transitions, making it a convenient and practical choice for parents looking to transition their little one from swaddling.