To provide the correct level of comfort and support as your child grows up. Most mattresses are either one-sided or dual-sided but are the same on each side. With the DuoCore, you are essentially getting two mattresses in one. On the baby side, you have a softer side that is suited to a baby that is less than 12kg. Flip over to the toddler side and you have a firmer side that provides more support for a toddler over 12kg. Therefore, you are always assured that your child is sleeping on a surface that is providing the right balance of comfort and support for their current stage of development.