The 600ml Ultraflask is a collapsible sport bottle with a versatile bite valve. Perfect for runners as it's clean, compact and easy to use.
Hydrapak says:
Go big. The largest of our ultra-light series, the UltraFlask 600 holds more so you can go the distance. Its soft material allows it to fit snugly in most vest pockets and it shrinks as you drink to minimize water movement.
Hydrapak's 600ml Ultraflask is perfect for use with running vests and packs. The long tube allows you to access your drink without removing the flask when used in chest/shoulder straps.
The bite valve can also be used without the tube and mounted straight on to the cap for hand held use.
Not only does the flask collapse for storage, it actually collapses as you drink, preventing that annoying sloshing when your on the move.