HydraPak SoftFlask Speed 500ml - Low-Profile Compressible Flask

In this review the HydraPak SoftFlask Speed 500ml is assessed as a lightweight, low-profile solution for runners and pack hikers who need a compact, fast-refilling bottle. The single biggest reason to buy is its combination of a tapered, pinch-welded base that fits snugly in hydration vest pockets and a one-handed SpeedFill cap that makes refill stops at aid stations quick and reliable. For anyone who values minimal movement, fast access to fluids and gear that packs away when empty, this flask delivers a focused, practical design.

Key Features

• Low-profile tapered shape: The pinch-welded base and soft material create a slim, tapered flask that slips into most vest and pack pockets without bulging or bouncing.
• Collapsible design: The soft TPU body conforms to pocket shapes and shrinks as you drink, which reduces sloshing and makes it easy to pack down when empty.
• SpeedFill cap: The flip-open SpeedFill cap pops open with a side tab for one-handed refills and snaps closed with an audible click to reduce spills.
• Bite valve seal: The self-sealing silicone bite valve delivers sips on demand while preventing drips when not in use, keeping pockets and gear dry.
• Filter compatibility: Accepts 42mm threaded backcountry filters so it can be used with simple filter caps for treated water on longer outings.
• Lightweight construction: At just grams of mass, the soft materials keep carried weight low for fast-paced activities.

Who It's For

The SoftFlask Speed 500ml is aimed at trail runners, fastpackers and triathletes who carry fluids in slim vest pockets or running packs and who need quick refills at aid stations. Its tapered shape and low weight make it ideal for shorter runs or events where a full bladder is unnecessary but on-demand sipping matters.

Those who want a rigid bottle that stands upright on a table, carries ice long-term, or prefers a larger capacity for extended solo hikes should look elsewhere; this flask is optimized for light weight, compact storage and fast access rather than cold retention or high-volume storage.

Pros & Cons

Pros

• Very low profile when loaded, which reduces bounce and fits most vest pockets comfortably.
• SpeedFill cap allows rapid, single-handed refills at aid stations or on the trail.
• Collapsible body shrinks as you drink, minimizing movement and packing away neatly when empty.
• Compatible with common 42mm filters for simple backcountry water treatment.

Cons

• Not insulated, so it does not keep liquids cold for long and is not ideal for ice storage.
• Soft walls mean it will not stand upright on hard surfaces and can feel flimsy compared with rigid bottles.

Specifications

Capacity	500 mL / 17 fl oz
Weight	46 g / 1.6 oz
Dimensions	260 mm x 80 mm / 10.2 in x 3.1 in
Materials	TPU, PP, Silicone, POM, 304SS
Included	SoftFlask 500ml, SpeedFill Cap, Bite Valve, Care Instructions

Our Verdict

The HydraPak SoftFlask Speed 500ml is a practical, well-executed flask for runners and pack users who prioritize low weight, a snug fit and fast refilling. It is good value for anyone who needs a compact drinking solution that shrinks away as you drink; however, those needing insulation or a rigid bottle should consider alternatives.

Frequently Asked Questions

Is the cap easy to open while running?
Yes, the SpeedFill cap uses a side tab that pops the cap open for single-handed operation and snaps closed with a click to avoid accidental openings.

Can I attach a filter to this flask?
Yes, the flask accepts 42mm threaded backcountry filters and is compatible with HydraPak 42mm filter-style caps for treated water use.

Will the flask leak in a pack?
The self-sealing silicone bite valve and SpeedFill cap are designed to prevent drips and leaks when closed, but users should ensure the cap is fully snapped shut after refilling.