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Quantity
1
Description
Custom-Built Soft Flask (450ml / 15oz) fits securely in the Endorphin Belt, keeping you hydrated without slowing you down.
Collapsible Design: This flexible flask shrinks as you drink, minimizing sloshing and freeing up space in your belt...
Reviews
4.4
24 ratings
5
4
3
2
1
My bite valve came apart after about 3 uses. Endorphin didnt just replace the bite valve. They sent me a whole new flask. Excellent customer service.
C
Cliff · August 7, 2026
Good size to fit in the belt. However the mouthpiece restricts the flow of water too much. It would be nicer if more water came out with each sip
A
Anonymous · 4 days ago
Excellent flasks! Enjoyed using the one that came with the belt so much that I bought two more. It doesn't leak at all if locked. It's also easy to hold with your hand because of the grippy material. Getting it into the belt fully filled is a little bit tricky but with practice it's easy to do.