1Concave and convex, the size of the head fits the size of the baby. 2Designed according to the size of the baby, it can prevent the baby from rotating or moving. 3High quality material, soft and breathable, comfortable and does not irritate the skin. 4Hoop and loop buckle, adjustable elasticity, easy to adjust the baby's body. 5Widened lower part to give the baby ample room for activity.