Trusted by 25k+ Runners
250ml / 9oz
No-slosh Design
Fast And Accessible Hydration For Every Run
Trusted by 25k+ Runners
250ml / 9oz
No-slosh Design
Fast And Accessible Hydration For Every Run
Built for everyday miles when you want water on hand without carrying more than the run requires.
Stacks with the 450ml flask
for up to 700ml of total hands-free hydration on long runs.
Soft, flexible design
compresses as you drink to minimize movement and noise.
High-flow, self-sealing bite valve
delivers fast hydration without drips or leaks.
Twist-to-lock cap
adds an extra layer of security during hard efforts.
BPA-free, odor-resistant materials
built for frequent use and refills.
Soft, flexible design
compresses as you drink to minimize movement and noise.
High-flow, self-sealing bite valve
delivers fast hydration without drips or leaks.
Twist-to-lock cap
adds an extra layer of security during hard efforts.
BPA-free, odor-resistant materials
built for frequent use and refills.
Shaped to fit securely in the Endorphin Belt
for stable, hands-free carrying.
CHOOSE YOUR SIZE:
Free Shipping over $60
30-Day Risk Free
No-Bounce Guarantee
It is amazing as you think it is!
This belt and flask are a game changer and the customer support is second to none. No bounce, plenty of room, enough onboard hydration andnutrition, this belt has it all.
Frequently Bought Together:
Endorphin Running Belt
Everyday training essentials
Performance Hat
Keeps you cool on every run
Race Bib Toggles
Keeps your bib secure
$45
Features
250ml / 9oz capacity
Soft and flexible collapsible body
Twist-to-lock top: zero accidental leakage
Self-sealing high-flow bite nozzle: effortless drinking on the go
Easy-to-grip cap: simple to open, fill, and wash
Free from BPA, phthalates, and PVC
Color: black with white Endorphin logo
Fits the Endorphin Belt front pocket and rear compartment
Specs
Capacity: 250ml / 9oz
Weight: 29g
Materials: BPA-free, odor-resistant TPU
Care: hand wash, air dry with cap open
Shipping & Returns
Free shipping on orders $60+ US Orders
Free Returns US Orders
30-day risk-free returns US
Features
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 as your run progresses.
High-Flow Bite Valve: Equipped with a leak-resistant, self-sealing nozzle that provides quick sips without spillage.
Durable & Safe Materials: Made from BPA-free, odor-resistant materials that withstand frequent use and multiple refills.
Specs
450 ml capacity
Soft and flexible
Twist-to-lock top: zero accidental leakage
Self-sealing bite nozzle: effortless drinking on-the-go
Easy-to-grip cap: simple to open, fill, and wash
Free from BPA, phthalates, and PVC
Color: light gray and transparent
Weight: 33 g
Shipping & Returns
Free shipping and returns in Continental US over $60
30 day risk free trial
Features
Modular Carry System: Both flasks are sized for the Endorphin Belt. Run them together for 700ml of total capacity, or grab the one that fits the day. Front pocket, rear pocket, your call.
Collapsible Design: Each flask shrinks as you drink, minimizing sloshing and staying quiet and stable as your run progresses.
High-Flow Bite Valve: Leak-resistant, self-sealing nozzles on both flasks deliver quick sips without spillage and without breaking stride.
Twist-to-Lock Tops: Zero accidental leakage. Lock it, load it, forget about it.
Durable & Safe Materials: Made from BPA-free, odor-resistant materials that withstand frequent use and multiple refills.
Specs
450ml + 250ml capacity (700ml combined)
Soft and flexible construction
Twist-to-lock tops: zero accidental leakage
Self-sealing bite nozzles: effortless drinking on-the-go
Easy-to-grip caps: simple to open, fill, and wash
Free from BPA, phthalates, and PVC
450ml color: light gray and transparent
250ml color: black with white logo
Combined weight: 62 g
Shipping & Returns
Free shipping on orders $60+ US Orders
Free Returns US Orders
30-day risk-free returns US
Frequently Asked Questions
How is this different from the original Endorphin Soft Flask?
Same bite valve, same twist-to-lock cap, same materials, smaller size. The 450 is built for long runs and race day. The 250 is built for everyday miles when you want water on hand without the extra volume. Many runners carry both: the 450 in the rear compartment and the 250 in the front pocket for up to 700ml total.
Can I carry two flasks in the belt?
Yes. The belt fits one 450 in the rear compartment plus one 250 in the front pocket, or two 250s. Two 450s will not fit at the same time. The 250 was sized specifically to unlock these setups.
How do I get the water flowing?
The flask ships sealed and locked for health and safety. When you first open it, look for the arrows and on/off markings on the cap. Bite the nozzle and twist the cap slightly in the on direction at the same time to fully open the flow. Twisting alone may not release the full amount of water.
How do I clean the flask?
Rinse the cap and flask thoroughly after each use with warm, soapy water, and then let them air dry completely. The bite valve can also be cleaned with a drinking straw brush. The cap may be stored in the freezer to prevent mold.
Will it fit in the front pocket with my phone?
The front phone pocket is not designed to hold both the 250ml Soft Flask and a full-sized phone at the same time. While it does physically fit, it can make both items harder to access and may increase the chance of your phone getting wet from condensation or leakage. For the best experience, we recommend carrying your phone in the front pocket and the flask in the rear hydration pocket.
What is your return policy?
30-day risk-free returns in the US.
Designed for Runners Who Demand More
Shop
Features
Testimonials
Contact Information
The Endorphin Belt Team
Endorphin Running Company, LLC
Soft Flask 250ml
Tested. Proven.
Secure checkout