Age: From newborn up to 15months (at least 3.5 kg up to 12 kg) Materials: 60% cotton and 40% polyester. Waist belt and flexible carrying for superior comfort: New, adjustable design with an ergonomic waist belt allows flexible carrying in a variety of ways. Extra soft and durable fabric: Made from a soft, durable cotton mix. Non-chafing seams. Grows with baby: BabyBjorn Baby Carrier Miracle is designed to fit your newborn perfectly from day one and "grows" with baby thanks to an innovative size adjustment buckle on the inside of the baby carrier.