Zerk 20 UL Daypack

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 20 is 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