The ergonomic design of the carrier ensures that your baby is in the correct sitting position to encourage proper hip, pelvis and spine growth. It does this by distributing most of the baby's weight between its hips and thighs. The design also considers the health and comfort of parents. The carrier balances the baby's weight to the parents' hips and shoulders, reducing physical stress. The padded waist belt supports the lumbar area plus 1" thick padding in the shoulder straps. It can be worn on front, back or hip and can easily be changed from one to the other. Ergo is perfect for when baby is too heavy for a sling or for when you plan on carrying your baby for extended periods of time, especially for hiking and walking. Unlike other frame back packs, with the ERGO the baby is right against your back so their weight seems less. When carrying a traditional hard frame back pack, your baby's center of gravity is further from your body and can be awkward and feel heavier.