The head accounts for less body weight and requires harder support to keep the cervical spine and spine relaxed at a natural level to promote blood circulation.
The shoulder is the broadest part of the body. Sleeping on the side produces the greatest pressure. It requires a soft and larger recessed space to release the pressure, effectively avoiding the arm's long-term paralysis, maintaining a healthy level of the spine, and enjoying sleep with zero pressure.
The waist is the narrowest part of the body. It needs hard support from the mattress to fit the waist curve and keep the spine straight. In this way, it can effectively reduce the number of flips and prolong sleep time.
The hip occupies a larger body weight and is wider than the waist. It needs moderate softness and a slightly smaller pressure relief than the shoulders to maintain a straight spine.
The thighs follow the curve of the hips till the knee joints. It needs the same hardness of zone 3, allowing the legs to stretch freely.
The hardness needed for the calves and ankle joints is the same as that of the shoulders in Zone 2, allowing the legs to fit and relax naturally.
The feet correspond to zone 1 and the support needed is preferrably hard. The symmetrical support design makes the mattress available from both ends.