Zerk 20 UL Daypack

NEW FOR 2026! Designed for a Viking, built for weekend warriors, this multi-sport day pack is ideal for long hikes and quick summit ascents. Now with increased modularity, new ultralight materials and additional convenience on the trail. Our new Zerk UL series truly 'Goes Where You Go'!

Color
DARKNIGHT

Inspired by a Viking, used by weekend warriors. Meet the Zerk 20, the ultimate ultralight daypack.

Built for grueling day hikes and challenging summits, the Zerk 20is the little sibling to our award winning Zerk 40L; loaded with all the features of the original but in a smaller, multi-sport form factor for weekend-slaying and personal bests. Developed in collaboration with The Real Hiking Viking as an out-and-back training pack to tackle the toughest terrain over long miles, this ultralight daypack will be your go-to for fast and light, all day outings. A Mountainsmith staff favorite!

For this new addition to the Zerk UL series, we've added Zerk accessory compatibility with our Zerk 3L Loki Lumbar and Zerk 7L Toplid enabling you to turn this 20L daypack into a minimalist 30L backpack for hardcore overnights. We've also included modular compressions straps (x2) and field serviceable bungees; not only increasing your versatility on the trail, but also allowing you to strip the weight when minimalism is key. 


Additional upgrades for 2026:

  • Materials upgraded to Robic® Nylon X-Grid Extreema (UHMWPE) Ripstop with UTS coating for both the 210d fabric (bottom panel, backpanel and reinforcement areas) and 100d fabric (main body)
  • A new front panel zippered security pocket for improved organization of trail valuables
  • Upper stretch mesh pocket on left side panel for quick access items (Avocados anyone?)
  • Compatibility with our new Zerk 3L Loki Lumbar pack which acts as a chest rig on the ZERK 20 shoulder straps
  • Compatibility with our new Zerk 7L Toplid accessory, increasing your carrying capacity by an additional 7L, great for when you need to carry extra gear for weather

FEATURES

  • Roll top closure with opposing SR buckles for self closing roll top or for side panel attachment with removable straps
  • Extra wide shoulder straps with dual adjustable sternum straps
  • 4 Large mesh front pockets on shoulder straps (2 per side) accommodate 500ml bottles, bear spray, cell phones, gps units, etc
  • Airflow EVA foam padded shoulder straps
  • Modular side compression straps (removable) for securing load throughout entire pack or discarding entirely
  • Customizable and removable front panel bungee system
  • Removable 1.5” waistbelt with Gatekeeper attachment hardware. Works with accessory Zerk 3L Loki Lumbar (Sold Separately)
  • Large main compartment holds up to 40 liters of gear with extra 4L storage in roll top area
  • Expansive front stretch mesh pocket for hauling extra layers
  • Reflective bungee and select webbing hits for increased visibility
  • Removable interior frame sheet (EVA / Atilon)
  • Dual side water bottle pockets with angled openings for easy access
  • Adjustable over-the-top V-shaped compression strap with SR buckle closure
  • Hydration bladder sleeve with hose port (Bladder Not Included)
  • Compatible w/ Zerk 7L Top-lid (Sold Separately) for extra carrying capacity
  • Bright yellow lining promotes visibility

MATERIALS

  • 210d Robic® Nylon X-Grid Extreema (UHMWPE) R/S UTS*
  • 100d Robic® Nylon X-Grid Extreema (UHMWPE) R/S UTS*
  • 840d x 100d Stretch Mesh*
  • 150d High Density Poly Liner*
  • YKK® Zipper
  • EVA Foam
  • *There are no intentionally added PFAS in this item

CALIFORNIA WARNING: Cancer and Reproductive Harm | www.P65Warnings.ca.gov

DIMENSIONS

  • 10” x 18” x 6” (L x H x D)

VOLUME

  • 1220 in3 / 20 L
  • 1400 in3 / 23 L (Extended Roll Top)

CAPACITY

  • Waistbelt Size Range: 28"-48"
  • Torso Range: 15"-19"
  • Weight Load: Suggested up to 20 lbs, but will accommodate 50% more (ie., 30 lbs) for your next sufferfest

WEIGHT

  • 1 lb 12 oz / 0.79 kg
  • 1 lb 6 oz / 0.7 kg (Stripped)

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