SwaddleDesigns Transitional Zzzip Me Swaddle Sack 3-6m Yellow Double Zip New The SwaddleDesigns Transitional Zzzip Me Swaddle Sack in yellow is a cozy sleeping bag designed for babies aged 3-6 months. Made from fleece material, this unisex swaddle sack features a unique double zip design for easy dressing and diaper changes. With a super soft Yellow fleece with soft trim This U.S. made swaddle sack is perfect for keeping your little one warm and snug during naptime or bedtime.