Zpacks Women's Arc Haul Ultra 40L Backpack

The Zpacks Arc Haul Ultra 40L is a women's-specific thru-hiking backpack weighing 575 g, roughly 14.4 g per litre — the smallest and, per litre, the least weight-efficient of the Arc Haul Ultra volumes, since the carbon-fibre Arc Frame and hardware weight stay much the same while the fabric shrinks. It shares the Ultra 100X main fabric, adjustable back length and padded hip belt of the larger sizes, so fit and load transfer don't change with volume. At 40 litres it suits shorter thru-hikes, warm-season trips, or hikers with a genuinely minimal gear list who don't need room for bulky cold-weather layers or a bear canister. It's not the pack to reach for on longer resupply stretches where food volume adds up fast; for those, the 50L or 70L in the same range carry more without changing the frame or hip belt system.