Mountainsmith
Zerk 40L Pack
Best lightweight pack for long distance hikers seeking accessible storage.
Designed for long-distance trekking, this pack prioritizes a balance of weight and durability. It features a frameless construction with a padded back panel, offering a streamlined profile for fast-paced movement. The roll-top closure and multiple external storage options, including large mesh pockets, provide quick access to essentials while on the move. Built with high-tenacity materials, it withstands rugged trail conditions while maintaining a lightweight feel. The design emphasizes comfort and accessibility, making it a reliable choice for those looking to cover significant mileage efficiently.
$219.95
More Zerk Options
Owner Satisfaction
4.5
/ 5
Category Rank
5018
/ 15434
#5018 in Backpacks
Price vs Category Average
+102%
Above average
Capacity
40
/ L
Who it's for
- Thru-hikers prioritizing efficiency and high-mileage days
- Backpackers seeking a stable, bounce-free carry on technical terrain
- Ultralight enthusiasts needing gear that survives rugged trail conditions
Who should skip it
- Hikers carrying heavy luxury items or excessive water weight
- Organized travelers who want quick access to interior gear
- Summer hikers prone to overheating in humid environments
Performance breakdown
Weight-to-Capacity Ratio
Ultralight construction makes carrying 40 liters feel surprisingly effortless on trail.
Accessibility
Large mesh pockets allow for quick gear retrieval without removing the pack.
Load Management
Roll-top closure and compression straps keep smaller loads stable and secure.
Durability
High-tenacity nylon ripstop handles abrasive rock and dense brush with ease.
Structural Support
Frameless design prioritizes speed but requires careful packing for optimal comfort.
Customization
Removable waistbelt and frame sheet offer versatile options for different hiking styles.
Key Specs
Capacity
40L
Weight
1.81 lbs
Dimensions
22 inches x 14 inches x 10 inches
Material
210d EXTREEMA Recycled Nylon Ripstop
Max Load Capacity
30 lbs
Frame Type
Frameless
Know before you buy
The Zerk 40L is designed for lightweight, fast-paced trekking with a maximum load capacity of 30 lbs. Because it lacks a traditional internal frame, you will need to pack carefully to ensure the load remains balanced and comfortable against your back.
Yes, the 1.5-inch waistbelt is fully removable. This is a great feature if you are carrying a lighter load and prefer more freedom of movement or want to reduce the pack's overall bulk.
The EVA Atilon frame sheet provides structure and rigidity to the back panel, which helps the pack keep its shape and improves airflow. You can remove it if you want to save weight or need to roll the pack up for storage, though you will lose some of that structural support.
The roll-top closure is highly effective at keeping your gear secure and allows you to adjust the volume of the pack based on how much you are carrying. While it keeps out dust and light rain, it is not fully waterproof, so you should still use a pack liner or dry bags for critical items during heavy downpours.
This material is specifically chosen for its high strength-to-weight ratio, making it quite rugged for its class. It holds up well against standard trail wear and tear, though you should still exercise caution when bushwhacking through dense, thorny vegetation.
Still have a question?
Ask Hayley anything about this product before you decide.