Height Adjustable- its height can be adjusted in 3 steps. 40cm, 43cm,46cm. depends on the babys height Rollover- The shape of the walker is much more stable. It reduces the triangle stable mechanics. According to the principle of mechanics G=MG, the lower the centre of gravity, the more stable. The bottom is widened to enlarge U-SHAPED to ensure it does not roll over Diaper like shape- Experts in diaper work together to create this type of a shape. It does not affect hip-bone development. It effectively supports body weight on the legs and reduces leg pressure Material of the seat- The material which is used in the backrest is PU material which is environmental friendly and waterproof