Happiest Baby Snoo Sleep Sack New in box Size medium: 12-18lbs Color: ivory SNOO Sack and SNOO Comforter Sack (our warmer wrap), were specially designed to be used in SNOO Smart Sleeper to help babies sleep safer, longer, and happier! And because SNOO Sack was created by world-renowned pediatrician Dr. Harvey Karp, you can trust that every detail was designed with baby safety and parent sanity in mind!