Hyperlite Mountain Gear Unbound 55

The Unbound 55 is the larger sibling of the Unbound 40, aimed at longer thru-hikes where more room is needed for multi-day food and gear. The 55 L main body plus a 9 L external stretch pocket bring total capacity to 64 L. The Dyneema Composite Hybrid fabric is reinforced at the hip and bottom (DCH150) while the body uses the lighter DCH50 — a typical weight-saving approach that concentrates the tougher fabric where wear is highest. The carry system — removable aluminum stay, padded contact back panel, and chest strap — matches the smaller model, as does the roll-top closure, front pocket, and two side pockets. At 879 g, the ratio works out to 72.8 L/kg, or 13.7 g per liter, a somewhat better figure than the Unbound 40, which is typical at larger volumes since weight grows more slowly than capacity. It is aimed primarily at multi-day treks and thru-hiking trips carrying heavier loads.