HydraPak UltraFlask Speed 500ml Running Soft Flask

Stable, Compressible Hydration for Long Runs

Best For: Trail running, long-distance training, racing, and fastpacking when you want 500 ml of flexible hydration that stays secure in a running vest.

Stable vest hydration. The UltraFlask Speed 500ml is a running soft flask with a wider shape and structured 3D welded bottom that helps it sit securely in vest pockets as it empties. Its soft TPU construction compresses as you drink, reducing bulk and helping limit water sloshing on the move.

Refill without fuss. The SpeedFill cap opens quickly for easy refills at aid stations or trailside taps, while the high-flow bite valve delivers water without needing to remove the cap. The 42 mm opening also makes it easier to add ice, mix electrolytes, or use a compatible 42 mm water filter.

Lightweight race-day kit. At just 42 g, this flask adds very little weight to a hydration vest while still using abrasion-resistant TPU and RF-welded seams for durability. It's a particularly useful setup for long trail runs and races where quick refills and compact storage matter.

Features & Benefits

• SpeedFill cap — allows quick refills without removing the cap from the flask.
• 3D welded bottom — adds structure and stability in running vest pockets.
• Compressible TPU design — shrinks as you drink to reduce bulk and water movement.
• High-flow bite valve — provides steady drinking flow with an auto-sealing valve.
• 42 mm wide opening — makes it easy to add ice, mix electrolytes, or use a compatible water filter.