Getting a drink or checking a small item should not require unpacking the entire day's load. The Mountainsmith Zerk 20 UL Daypack includes shoulder-strap storage as part of its day-hiking layout.
Twenty Liters With Reachable Small Storage
Mountainsmith describes a 20-liter main compartment with an extra three liters in the roll-top area. The wide shoulder straps carry mesh pockets intended for appropriate bottles and small equipment.
- Main volume: 20 liters.
- Closure: Roll top.
- Access: Shoulder-strap mesh pockets and side bottle pockets.
- Support: Removable internal frame sheet.
Keep Day Gear Easy to Reach
I would use the accessible pockets for the items that interrupt a walk most often, while keeping suitable weather layers and less-used supplies in the main bag. A deliberate arrangement can reduce stopping and searching.
The shoulder pockets still need a fit check with the actual bottles or devices. A manufacturer's example of a suitable item does not make every version of that item the same shape.
Modularity Does Not Mean Everything Is Included
The Zerk 20 supports separate Zerk accessories, including a top lid and a small lumbar component. That can create options, but I would compare the pack as supplied before adding capacity and expense.
It also has a hydration sleeve and hose port, with a bladder not included. A planned drinking setup therefore needs either compatible bottles or the appropriate separate reservoir.
A Daypack First
I would choose this for a day load that fits comfortably and benefits from the reachable storage. If overnight equipment is always part of the plan, the larger Zerk models may be a more straightforward comparison. The appeal here is a daypack that stays focused on the day's needs, with optional additions available when there is a specific reason for them.
Other Options to Compare
Mountainsmith Divide EVO Daypack →
Mountainsmith Mayhem EVO 30L Backpack →



