Mountainsmith Zerk 40 – 2024

This 2024 iteration of the Mountainsmith Zerk 40 shifts the emphasis toward fastpacking, pairing the same 210D EXTREEMA recycled nylon ripstop (UHMPE) body with a vest-style shoulder harness and stretch pockets designed for a run-hike rhythm rather than a static hiking gait. At 822 g it sits within a gram of the standard Zerk 40, but the fit system is built for a narrower torso range of 41–48 cm and a rated maximum load of 13.6 kg — a reminder that the hipbelt here is stabilization-only, not load-bearing, so heavier packs will start to feel it on climbs. A DWR-treated finish adds water resistance beyond the base fabric, and the removable EVA frame sheet keeps weight adjustable. Dual ice axe loops, a daisy chain, and reflective elements round out a pack aimed at long trail runs and multi-day fastpacks rather than conventional backpacking with heavier gear.