The 4500 defines the word core. There is not a pack on the planet that can match the technology, comfort, features, or performance of the 4500 period. The 4500's molded foam matches your body curve for curve and a polycarbonate frame which transfers even the strangest loads with grace and comfort at half the weight and twice the strength of a traditional aluminium framed pack. The suspension is the "performance zone" — it is painfully obvious that most other companies just don't get it.