Mountainsmith Zerk 25 Ultralight Backpack

£135.99

A FASTPACK BUILT FOR SPEED, COMFORT, AND CUSTOMISATION 

Meet the Zerk 25, now available in a new, compact size! Back by popular demand, this pack is designed for those who value speed and efficiency on mountain trails. Part of the growing Zerk Family, it’s the go-to choice for thru-hikers needing a fast and light pack where versatility and comfort are key. This latest update is packed with thoughtful features, including daisy chain attachment points, dual ice axe loops, dual side compression straps, and an embroidered design, all enhancing customisation and functionality. Whether you're heading out for a quick alpine climb or a wild camping trip, the Zerk 25 is built to handle whatever you throw its way.

FEATURES OF THE ZERK 25 ULTRALIGHT BACKPACK 

  • 1.5” removable waistbelt
  • Large main compartment holds up to 23 litres of gear
  • Lid top closure with side compression SR buckles. Front SR buckle closure
  • Side compression straps for securing load throughout entire pack
  • Large side water bottle pockets with angled opening to easily remove and insert items while on the go
  • Expansive front mesh pocket for hauling bulky gear
  • Large mesh side stash pockets with angled opening for easy reach
  • Reflective screen printing and cord loops for low light visibility
  • Front cord loops can be configured with bungee cord (included)
  • Extra wide shoulder straps with adjustable sternum strap (includes safety whistle)

What we think 

Co-designed with The Real Hiking Viking, a professional 'hike-really-long-distances-really-quickly', the ZERK 25 was born out of a need for an ultralight pack that can withstand the thousands of miles per year that The Real Hiking Viking already covers. Mountainsmith wanted to make sure that it would allow him to go farther, to hike longer, and to work more efficiently on the trail.  Over the course of 2 years of development, the ZERK 25 went through 4 iterations and over 5,000 miles of testing on the Wind River High Route, the Colorado Trail, The Tetons, and more.

  • Size + Specifications

    - MATERIALS
    210d EXTREEMA Recycled Nylon Ripstop (UHMPE)
    Recycled 210d nylon SD oxford
    Nylon 100D x Span 840D stretch mesh

    - DIMENSIONS
    20" x 12" x 6.25"
    Waistbelt max 48"
    Torso range 16" - 19"

    - VOLUME
    23 L

    - CAPACITY
    Up to 9kg

    - WEIGHT
    822g with accessories, 765g without accessories

  • Reviews

    "The Mountainsmith Zerk 25 is a multi-purpose daypack/fastpack with a vest-style shoulder harness and a non-load-bearing hip belt. It is remarkably comfortable and has a plethora of pockets that make it easy to organise and access your gear on the move. There is also plenty of secure closed storage to carry extra clothing and equipment. While switching from a conventional daypack to one with vest-style straps and storage takes some getting used to, I think you’ll find that the hybrid combination of daypack and fastpack features on the Mountainsmith Zerk 25 makes this pack a keeper for adventures near and far."

  • Weight

    765 g