Scientifically designed for self-soothing and sounder sleep. The gently weighted Zen One calms like your embrace by providing comforting pressure only where babies are naturally held. This secure feeling eases the womb to world transition and helps babies self-soothe through sleep disruptions, leading to deeper periods of sleep that are essential for healthy development. One size: - Age: 0-6 months - Weight: 7-18 lbs / 3.2-8.2 kgs - Height: 19-28 inches / 48-71 cms * When determining which size is best for your baby, look at the minimum weight, and the maximum height. Your baby should not be below the minimum weight, but they should have at least 2 inches to grow into the maximum height. Fabric details: - Made from 100% breathable cotton - Perfect for year-round comforts - TOG 1.5 Care details: - Wash in cold water on delicate cycle - Tumble dry on low heat